@misc{krim_smirnov_2024, title={Fundamental Mechanisms Underlying the Effectiveness of Nanoparticle Additives to Lubricants: 25 Examples Linking Nano- to Macroscale Friction}, volume={12}, ISSN={["2075-4442"]}, url={https://www.mdpi.com/2075-4442/12/6/225}, DOI={10.3390/lubricants12060225}, abstractNote={Studies of the fundamental origins of friction have undergone rapid acceleration in recent years by providing valuable information on the nanoscale mechanisms responsible for friction at the macroscopic level. Significant efforts have been directed at developing composite nanofluids and nanoparticle additives to unlock new tribological properties unattainable by traditional lubricants. The studies are now further evolving by developing methods to achieve active control over nano- and/or mesoscale friction through the application of magnetic and electric fields external to the contact. These methods constitute an area of rapidly growing interest, and they also illuminate how the performance of conventional lubricants could be enhanced through the synergistic addition of nanoparticles (NPs). This mini review highlights 25 publications that collectively reveal significant progress, as well as important outstanding challenges, to the fundamental understanding of how the addition of NPs impacts lubricant performance. The first two topics focus on how Quartz Crystal Microbalance (QCM) nanotribological response to solid contacts can be linked to macroscale friction coefficients in the boundary lubrication regime and how QCM response upon immersion into a liquid is linked to macroscale lubricity in the mixed and hydrodynamic regimes. The third and fourth topics highlight the pivotal role of nanoparticle charge and surface treatments, while also indicating that the rolling of nanoparticles is ineffective and/or detrimental. The fifth topic focuses on applications that demonstrate the tuning of friction by varying nanoparticle electric charge and/or an external electric potential. The highlighted literature was selected to demonstrate a range of experimental and theoretical research, to provide direct connections between the nanoscale and macroscale tribological attributes, and to emphasize environmentally friendly lubricating materials such as water-based nanofluids.}, number={6}, journal={LUBRICANTS}, author={Krim, Jacqueline and Smirnov, Alex I.}, year={2024}, month={Jun} }
 @article{figueroa_krim_hirano_2023, title={The Preface}, volume={17}, ISSN={["2666-5239"]}, DOI={10.1016/j.apsadv.2023.100445}, journal={APPLIED SURFACE SCIENCE ADVANCES}, author={Figueroa, Carlos A. and Krim, Jacqueline and Hirano, Motohisa}, year={2023}, month={Oct} }
 @article{seed_acharya_nunn_smirnov_krim_2023, title={Tribotronic and electrochemical properties of platinum-nanofluid interfaces formed by aqueous suspensions of 5 and 40 nm TiO<sub>2</sub> nanoparticles}, volume={159}, ISSN={["1089-7690"]}, url={https://doi.org/10.1063/5.0155504}, DOI={10.1063/5.0155504}, abstractNote={Nanoparticles (NPs) can be highly beneficial as additives to lubricating fluids, and the tribotronic response of charged NPs tuned by external fields represents an area of great technological potential. Tribotronic response, however, is expected to be highly size dependent, which represents a significant design challenge. To explore this issue, quartz crystal microbalance and cyclic voltammetry were employed to characterize nanotribological and electrochemical behavior of platinum–nanofluid interfaces formed by aqueous suspensions of different-sized negatively charged titanium dioxide (TiO2) NPs. Suspensions of 5, 40, and 100 nm NPs were all observed to reduced interfacial frictional drag forces upon introduction into pure water in zero field conditions, with reductions for the 40 nm NPs about twice those of 5 nm particles at comparable concentrations. Suspensions of 100 nm NPs produced even greater reductions, but rapidly precipitated from the suspension when left unstirred. NPs were also driven to and from Pt electrode surfaces by applying external electric fields with varying amplitudes and modulation frequencies. For electric fields of sufficient amplitude and duration, the 40 nm TiO2 nanosuspension exhibited tribological properties consistent with a reversible electrophoretic deposition of the NPs, accompanied by changes in the electrochemical attributes and increasing interfacial drag. The 5 nm NP properties were consistent with progressive reductions in interfacial drag forces at the NP–suspension interface linked to field-induced increases in concentration.}, number={11}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Seed, C. M. and Acharya, B. and Nunn, N. and Smirnov, A. I. and Krim, J.}, year={2023}, month={Sep} }
 @article{acharya_seed_krim_2022, title={Shear activation of ZDDP reaction films in the presence and absence of nanodiamonds}, volume={7}, ISSN={["2666-5239"]}, DOI={10.1016/j.apsadv.2022.100214}, abstractNote={We explore the impact of shear stress and nanodiamond (ND) additives on the formation temperatures of thermal- and tribo- reaction films of steel samples immersed in basestock oils containing zinc dialkyl dithio-phosphate (ZDDP) additives. The measurements were performed in-situ using a quartz crystal microbalance (QCM) immersed in oil, oil plus ZDDP, and oil plus ZDDP-ND blends over the temperature range 25 200 °C. ZDDP reaction film formation temperatures were observed to decrease with contact stress and be similar in value to ZDDP-ND blends. ND were observed to be embedded in the reaction films, consistent with prior observations for Tricresyl phosphate (TCP) ND blends, and also consistent with the presence of both primary and secondary reaction products in the films. In addition, the ZDDP+ND reaction tribofilms were observed to be thicker, rougher and more adhesive than those formed with only ZDDP.}, journal={APPLIED SURFACE SCIENCE ADVANCES}, author={Acharya, Biplav and Seed, Caitlin M. and Krim, Jacqueline}, year={2022}, month={Feb} }
 @article{seed_acharya_krim_2021, title={QCM Study of Tribotronic Control in Ionic Liquids and Nanoparticle Suspensions}, volume={69}, ISSN={["1573-2711"]}, DOI={10.1007/s11249-021-01461-7}, number={3}, journal={TRIBOLOGY LETTERS}, author={Seed, C. M. and Acharya, B. and Krim, J.}, year={2021}, month={Sep} }
 @article{seed_acharya_perelygin_smirnov_krim_2021, title={Tribotronic control and cyclic voltammetry of platinum interfaces with metal oxide nanofluids}, volume={566}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2021.150675}, abstractNote={Nanotribological and electrochemical behavior of platinum-nanofluid interfaces are reported for aqueous suspensions of positively charged Al2O3 and negatively charged TiO2 nanoparticles, employing Quartz Crystal Microbalance (QCM) and cyclic voltammetry (CV) techniques. Tribotronic methods were employed to adjust the nanoparticles’ positions relative to Pt surface electrodes, and both voltammetry and tribological performance measures were observed to be highly sensitive to the adjustments. Interfacial friction levels were observed to be higher for both types of nanoparticles when electrostatically driven towards the surface. For electric fields of sufficient amplitude and duration, the TiO2 nanosuspension exhibited properties consistent with reversible electrophoretic deposition of the nanoparticles, accompanied by changes in the electrochemical attributes of the electrode itself. Overall, the study suggests a method for active tribological control and optimization of device performance in applications where suspensions of charged nanoparticles are present and can be exposed to external fields.}, journal={APPLIED SURFACE SCIENCE}, author={Seed, C. M. and Acharya, B. and Perelygin, V and Smirnov, A. and Krim, J.}, year={2021}, month={Nov} }
 @article{seed_acharya_krim_2020, title={Continuum Model Analysis of QCM Nanotribological Data to Obtain Friction Coefficients for 304SS Contacts Lubricated by Water and TiO2 Nanoparticle Suspensions}, volume={6}, ISSN={["2297-3079"]}, DOI={10.3389/fmech.2020.00072}, abstractNote={We report a study of the response of a Quartz Crystal Microbalance (QCM) to rubbing contacts in air, water and aqueous suspensions of 40 nm TiO2 nanoparticles. Measurements were performed with a contact comprised of 3 close-packed 304SS ball bearings situated symmetrically about the center of a 304SS QCM electrode with 2 nm rms roughness. Two continuum methods were employed to infer macroscale friction coefficients μ employing QCM nanotribological data recorded in the Cattaneo-Mindlin (CM) slip regime at vibrational amplitudes that varied between 1 and 17 nm. The “slope” Method 1 involved sweeps of the QCM amplitude of vibration as ball bearings were held in continuous contact with the oscillating electrode. The “contact” Method 2 obtained μ by analyzing the shifts in frequency and bandwidth that occur at a fixed uo to solve for μ. when ball bearings were brought in and out of contact with the QCM's electrode. The results for dry and water lubricated contacts compared favorably with macroscale friction coefficients reported in the literature. The model failed to adequately describe contacts lubricated with the NP suspension, but its continuum nature did not appear to be the dominant factor underlying failure. The failure was more likely attributable to either a lack of a CM slip regime when NP were present at the interface and/or the fact that the amplitude of vibration was close in size to the individual NP contacting regions, in violation of a key underlying assumption of the model.}, journal={FRONTIERS IN MECHANICAL ENGINEERING-SWITZERLAND}, author={Seed, Caitlin M. and Acharya, Biplav and Krim, Jacqueline}, year={2020}, month={Sep} }
 @article{seed_acharya_andrus_krim_2020, title={Correlation of high frequency QCM sphere-plate stiffness measurements with macroscopic frictional contacts in thin film and bulk stainless steel materials}, volume={306}, ISSN={["1873-3069"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85082119223&partnerID=MN8TOARS}, DOI={10.1016/j.sna.2020.111913}, abstractNote={We compare friction coefficient values μ for stainless steel contacts, obtained directly using a ball on disk tribometer and/or a basic “da Vinci” method, with values inferred from two microscale analysis methods reported in the literature that treat the response of a Quartz Crystal Microbalance (QCM) to rubbing contacts with one or more ball bearings. The microscale analysis methods both employ a Cattaneo-Mindlin slip scenario to relate contact stiffness to QCM response. Analysis Method 1 involves sweeps of the QCM amplitude of vibration while ball bearings are held in continuous contact with the oscillating electrode. It obtains μ from the slope of the associated frequency or bandwidth shift trace. We find that this method yields values for μ that compare favorably with macroscale values when the bandwidth dependence on vibrational amplitude is utilized. Method 2 obtains μ by analyzing the shifts in frequency and bandwidth that occur when ball bearings are brought in and out of contact with a QCM’s oscillating electrode at a fixed vibrational amplitude. We find that this method yields values for μ that compare favorably with macroscale values when the measurements are performed with a contact comprised of 3 close-packed ball bearings situated symmetrically about the center of the QCM electrode. Overall, the results validate the combination of assumptions employed in the analysis methods, and support the methods as a viable means for linkage of macro and nanoscale tribological measurements.}, journal={SENSORS AND ACTUATORS A-PHYSICAL}, author={Seed, Caitlin M. and Acharya, Biplav and Andrus, Rachel and Krim, Jacqueline}, year={2020}, month={May} }
 @article{su_krim_brenner_2020, title={Dynamics of Neutral and Charged Nanodiamonds in Aqueous Media Confined between Gold Surfaces under Normal and Shear Loading}, volume={5}, ISSN={["2470-1343"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85085662298&partnerID=MN8TOARS}, DOI={10.1021/acsomega.0c00073}, abstractNote={The dynamics of cubo-octahedral nanodiamonds (NDs) with three different surface treatments and confined in aqueous environments between gold surfaces under shear and normal loading conditions have been characterized via molecular dynamics (MD) simulations. The treatments consisted of carboxyl (−COO–) or amino (−NH3+) groups attached to the NDs, producing either negatively or positively charged NDs, respectively, and hydrogen-terminated surfaces producing neutral NDs. Simulations were performed in the presence and absence of induced image charges to explore the impact of electrostatic interactions on friction and surface deformation. Significant deformation of the gold surfaces was observed for negatively charged NDs placed between gold surfaces under external loads that were sufficient to displace water from the contact. Rolling and relatively high friction levels were also observed for the negatively charged NDs under the same conditions. In contrast, the neutral and positively charged NDs exhibited sliding behavior with only minor deformation of the gold surfaces. The results suggest that the size of the surface functional group plays a major role in determining whether NDs slide or roll on solid contacts. Higher friction levels were also observed in conjunction with induced image charges in the gold contacts. The results demonstrate how surface functionalization and surface-induced charges can work in combination to profoundly influence tribological performance.}, number={18}, journal={ACS OMEGA}, author={Su, Liangliang and Krim, Jacqueline and Brenner, Donald W.}, year={2020}, month={May}, pages={10349–10358} }
 @article{perelygin_voinov_marek_ou_krim_brenner_smirnova_smirnov_2019, title={Dielectric and Electrostatic Properties of the Silica Nanoparticle-Water Interface by EPR of pH-Sensitive Spin Probes}, volume={123}, ISSN={["1932-7455"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076155729&partnerID=MN8TOARS}, DOI={10.1021/acs.jpcc.9b08007}, abstractNote={Interfacial electrostatic properties of monodisperse silica nanoparticles (SiNPs) in aqueous suspensions as a function of bulk pH were characterized by spin labeling EPR of two ionizable nitroxides: (1) IMTSL (S-(1-oxyl-2,2,3,5,5-pentamethylimidazolidin-4-yl)methyl methanesulfo-nothioate) and IKMTSL (S-4-(4-(dimethylamino)-2-ethyl-5,5-dimethyl-1-oxyl-2,5-dihydro-1H-imidazol-2-yl). SiNPs of ca. 116 nm in diameter (by particle number) were synthesized using the Stober method and their surface was modified by silanization under harsh conditions to ensure robust attachment of the thiol-terminated ligands to the silica surface. These ligands were consequently modified with either IMTSL or IKMTSL to characterize the surface electrostatic potential of the nanoparticles from their EPR spectra. EPR titration data for these two pH-sensitive nitroxides allowed for differentiating the dielectric and electrostatic contributions to the interfacial properties of SiNPs. From such a titration at room temperature an effect...}, number={49}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, publisher={American Chemical Society (ACS)}, author={Perelygin, Vladislav and Voinov, Maxim A. and Marek, Antonin and Ou, Erkang and Krim, Jacqueline and Brenner, Donald and Smirnova, Tatyana I and Smirnov, Alex I}, year={2019}, month={Dec}, pages={29972–29985} }
 @article{acharya_pardue_su_smirnov_brenner_krim_2019, title={Nanotribological Performance Factors for Aqueous Suspensions of Oxide Nanoparticles and Their Relation to Macroscale Lubricity}, volume={7}, ISSN={["2075-4442"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85068241799&partnerID=MN8TOARS}, DOI={10.3390/lubricants7060049}, abstractNote={Quartz crystal microbalance (QCM) measurements of nanotribological properties of statistically diverse materials combinations of nanoparticles and substrate electrodes in aqueous suspensions are reported and compared to macroscale measurements of the same materials combinations for a subset of the nanoparticle combinations. Four ceramic nanoparticles, TiO2, SiO2, Al2O3, and maghemite (γ-Fe2O3) and ten substrate materials (Au, Al, Cr, Cu, Mo, Ni, Pt, SiO2, Al2O3, and SS304) were studied. The QCM technique was employed to measure frequency and motional resistance changes upon introduction of nanoparticles into the water surrounding its liquid-facing electrode. This series of experiments expanded prior studies that were often limited to a single nanoparticle - solid liquid combination. The variations in QCM response from one nanoparticle to another are observed to be far greater than the variation from one substrate to another, indicating that the nanoparticles play a larger role than the substrates in determining the frictional drag force levels. The results were categorized according to the direction of the frequency and motional resistance changes and candidate statistical performance factors for the datasets were generated. The performance factors were employed to identify associations between the QCM atomic scale results and the macroscale friction coefficient measurements. Macroscale measurements of friction coefficients for selected systems document that reductions (increases) in motional resistance to shear, as measured by the QCM, are linked to decreases (increases) in macroscale friction coefficients. The performance factors identified in the initial study therefore appear applicable to a broader set of statistically diverse samples. The results facilitate full statistical analyses of the data for identification of candidate materials properties or materials genomes that underlie the performance of nanoparticle systems as lubricants.}, number={6}, journal={LUBRICANTS}, publisher={MDPI AG}, author={Acharya, Biplav and Pardue, Tyler N. and Su, Liangliang and Smirnov, Alex I. and Brenner, Donald W. and Krim, Jacqueline}, year={2019}, month={Jun} }
 @article{khajeh_krim_martini_2019, title={Synergistic effect of nanodiamonds on the adsorption of tricresyl phosphate on iron oxide surfaces}, volume={114}, ISSN={["1077-3118"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85065120303&partnerID=MN8TOARS}, DOI={10.1063/1.5093425}, abstractNote={Nanodiamonds (NDs) have potential uses in many applications, including as additives for liquid lubricants where they may be combined with more traditional chemicals, such as tricresyl phosphate (TCP), to form protective films on sliding surfaces. It has been shown that NDs can function synergistically with TCP to facilitate film formation on air baked iron. Here, reactive molecular dynamics simulations of TCP and NDs on an amorphous iron oxide surface reproduce experimental observations of the temperature at which film formation begins with NDs present and the effect of NDs on film composition. Analysis of chemical bonding in the simulations shows that the film formed in the presence of NDs comprises NDs and TCP that are both directly and indirectly bonded to the surface. Notably, the amount of phosphorus in the film, which is important for surface protection, is increased by TCP molecules that are indirectly bonded to the surface via NDs, which suggests that indirect bonding is one mechanism by which NDs facilitate film growth. The synergy of NDs and TCP has important implications for the development of NDs as emerging lubricant additives which must function with existing additives such as TCP in many applications.}, number={17}, journal={APPLIED PHYSICS LETTERS}, author={Khajeh, Arash and Krim, Jacqueline and Martini, Ashlie}, year={2019}, month={Apr} }
 @article{khajeh_krim_martini_2019, title={Synergistic effect of nanodiamonds on the adsorption of tricresyl phosphate on iron oxide surfaces (vol 114, 171602, 2019)}, volume={114}, ISSN={["1077-3118"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85066729936&partnerID=MN8TOARS}, DOI={10.1063/1.5109887}, abstractNote={First Page}, number={21}, journal={APPLIED PHYSICS LETTERS}, author={Khajeh, Arash and Krim, Jacqueline and Martini, Ashlie}, year={2019}, month={May} }
 @article{acharya_seed_brenner_smirnov_krim_2019, title={Tuning friction and slip at solid-nanoparticle suspension interfaces by electric fields}, volume={9}, ISSN={["2045-2322"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076322350&partnerID=MN8TOARS}, DOI={10.1038/s41598-019-54515-1}, abstractNote={Abstract}, number={1}, journal={SCIENTIFIC REPORTS}, author={Acharya, B. and Seed, C. M. and Brenner, D. W. and Smirnov, A. I. and Krim, J.}, year={2019}, month={Dec} }
 @article{clark_behringer_krim_2019, title={Vibration can enhance stick-slip behavior for granular friction}, volume={21}, ISSN={["1434-7636"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85067335218&partnerID=MN8TOARS}, DOI={10.1007/s10035-019-0895-5}, abstractNote={We experimentally study the frictional behavior of a two-dimensional slider pulled slowly over a granular substrate comprised of photoelastic disks. The slider is vibrated at frequencies ranging from 0 to 30 Hz in a direction parallel to sliding. The applied vibrations have constant peak acceleration, which results in constant average friction levels. Surprisingly, we find that stick-slip behavior, where stress slowly builds up and is released in intermittent slips, is enhanced as the frequency of vibration is increased. Our results suggest that increasing the frequency of vibration may help to combine many smaller rearrangements into fewer, but larger, avalanche-like slips, a mechanism unique to granular systems. We also examine the manner in which the self-affine character of the force curves evolves with frequency, and we find additional support for this interpretation.}, number={3}, journal={GRANULAR MATTER}, author={Clark, Abram H. and Behringer, Robert P. and Krim, Jacqueline}, year={2019}, month={Aug} }
 @article{pardue_acharya_curtis_krim_2018, title={A Tribological Study of γ-Fe2O3 Nanoparticles in Aqueous Suspension}, volume={66}, ISSN={1023-8883 1573-2711}, url={http://dx.doi.org/10.1007/S11249-018-1083-1}, DOI={10.1007/S11249-018-1083-1}, number={4}, journal={Tribology Letters}, publisher={Springer Science and Business Media LLC}, author={Pardue, T. N. and Acharya, B. and Curtis, C. K. and Krim, J.}, year={2018}, month={Sep} }
 @article{acharya_pardue_avva_krim_2018, title={In situ, real time studies of thermal reaction film formation temperatures for iron and 304SS surfaces immersed in 5% tricresyl phosphate in base oil}, volume={126}, ISSN={["1879-2464"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85047256526&partnerID=MN8TOARS}, DOI={10.1016/j.triboint.2018.04.034}, abstractNote={The temperature at which TCP forms a thermal reaction film with Fe and 304SS surfaces has been measured in real time, in situ liquid environments utilizing a QCM immersed in a synthetic dibasic ester base stock containing 5% TCP, and observed to be 210 °C. The thermal reaction films were characterized by AFM, and observed to be uniform on Fe and non-uniform and nodular in nature on 304SS substrates, with the thicknesses in the range of 60–100 nm. The chemical composition of the thermal reaction films was studied with EDS. The methods employed here demonstrate an effective means for screening of reaction film formation, and are extendable to systems involving multiple additives and/or complex metal composite materials.}, journal={TRIBOLOGY INTERNATIONAL}, author={Acharya, B. and Pardue, T. N. and Avva, K. S. and Krim, J.}, year={2018}, month={Oct}, pages={106–115} }
 @article{su_krim_brenner_2018, title={Interdependent Roles of Electrostatics and Surface Functionalization on the Adhesion Strengths of Nanodiamonds to Gold in Aqueous Environments Revealed by Molecular Dynamics Simulations}, volume={9}, ISSN={1948-7185}, url={http://dx.doi.org/10.1021/ACS.JPCLETT.8B01814}, DOI={10.1021/ACS.JPCLETT.8B01814}, abstractNote={Molecular dynamics simulations demonstrate that adhesion strengths as a function of charge for aqueous nanodiamonds (NDs) interacting with a gold substrate result from an interdependence of electrostatics and surface functionalization. The simulations reveal a water layer containing Na+ counterions between a negative ND with surface -COO- functional groups that is not present for a positively charged ND with -NH3+ functional groups. The closer proximity of the positive ND to the gold surface and the lack of cancelation of electrostatic interactions due to counterions and the water layer lead to an electrostatic adhesion force for the positive ND that is nearly three times larger than that of the negative ND. Prior interpretations of experimental tribological studies of ND-gold systems suggested that electrostatics or surface functionalization could be responsible for observed adhesion strength differences. The present work demonstrates how these two effects work together in determining adhesion for this system.}, number={15}, journal={The Journal of Physical Chemistry Letters}, publisher={American Chemical Society (ACS)}, author={Su, Liangliang and Krim, Jacqueline and Brenner, Donald W.}, year={2018}, month={Jul}, pages={4396–4400} }
 @article{goodman_bililign_keller_kenny_krim_2018, title={Simultaneous stress and mass change measurements arising from laser induced detuning of a quartz crystal microbalance}, volume={124}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.5029487}, DOI={10.1063/1.5029487}, abstractNote={We report a study of the frequency response of AT and BT cut Quartz Crystal Microbalances (QCMs) to laser illumination. AT and BT cut QCMs have a similar response to mass adsorption but the opposite frequency response to stress levels, allowing the individual contributions to stress and mass desorption induced by the laser light to be quantitatively investigated. A detailed analysis of the transient thermal behaviors in the quartz crystals has also been performed, which yields stress levels that are consistent with the observed results. Our results quantitatively confirm previous suggestions that radial compressive stress is a dominant contributor to the response of the QCM to laser illumination. They also establish a theoretical framework for the analysis of the transient phenomenon to infer temperature shifts and radial stress levels in the system irrespective of whether both AT and BT cut crystals are utilized.}, number={2}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Goodman, L. H. and Bililign, E. S. and Keller, B. W. and Kenny, S. G. and Krim, J.}, year={2018}, month={Jul}, pages={024502} }
 @article{acharya_avva_thapa_pardue_krim_2018, title={Synergistic Effect of Nanodiamond and Phosphate Ester Anti-Wear Additive Blends}, volume={6}, ISSN={2075-4442}, url={http://dx.doi.org/10.3390/lubricants6020056}, DOI={10.3390/lubricants6020056}, abstractNote={Nanodiamonds are known to improve tribological performance when added to lubricants, but their impact on additives that may already be present in the lubricant is poorly documented. Here, we report on a study of their effects on thermal reaction films formed from tricresyl phosphate (TCP) on Fe substrates immersed in a dibasic ester basestock when blended with TCP. Thermal reaction film formation temperatures were recorded in-situ by monitoring the reaction film formation on both Fe and air baked Fe surfaces using a quartz crystal microbalance (QCM). The nanodiamonds were found to raise the thermal reaction film formation temperature by 18 °C, possibly by raising the activation energy for the reaction, but they were not observed to affect the thickness or rate of formation of the films. The nanodiamonds, moreover, were observed to trigger thermal reaction film formation on air baked Fe surfaces that otherwise were highly resistance to reaction film formation. The surface morphology, roughness, and thickness of the thermal reaction films, as measured by atomic force microscopy (AFM), are reported as well as their chemical compositions, as studied with Electron Dispersive X-ray Spectroscopy (EDS). The coefficients of friction measured on the thermal reaction films during dry solid–solid contact are also reported.}, number={2}, journal={Lubricants}, publisher={MDPI AG}, author={Acharya, Biplav and Avva, Keshav and Thapa, Binita and Pardue, Tyler and Krim, Jacqueline}, year={2018}, month={Jun}, pages={56} }
 @article{fredricks_stevens_kenny_acharya_krim_2018, title={Tuning Nanoscale Friction by Applying Weak Magnetic Fields to Reorient Adsorbed Oxygen Molecules}, volume={4}, ISSN={["2410-3896"]}, url={http://www.mdpi.com/2410-3896/4/1/1}, DOI={10.3390/condmat4010001}, abstractNote={Sliding friction levels of thin (1–2 monolayers) and thick (~10 monolayers) oxygen films adsorbed on nickel and gold at 47.5 K have been measured by means of a quartz crystal microbalance (QCM) technique. Friction levels for the thin (thick) films on nickel in the presence of a weak magnetic field were observed to be approximately 30% (50%) lower than those recorded in the absence of the external field. Friction levels for thin films on gold were meanwhile observed to be substantially increased in the presence of the field. Magnetically-induced structural reorientation (magnetostriction) and/or realignment of adlayer spins, which respectively reduce structural and magnetic interfacial corrugation and commensurability, appear likely mechanisms underlying the observed field-induced reductions in friction for the nickel samples. Eddy current formation in the gold substrates may account for the increased friction levels in this system. The work demonstrates the role of magnetic effects in model systems that are highly amenable to theoretical studies and modeling.}, number={1}, journal={CONDENSED MATTER}, author={Fredricks, Z. B. and Stevens, K. M. and Kenny, S. G. and Acharya, B. and Krim, J.}, year={2018}, month={Dec} }
 @article{acharya_chestnut_marek_smirnov_krim_2017, title={A Combined QCM and AFM Study Exploring the Nanoscale Lubrication Mechanism of Silica Nanoparticles in Aqueous Suspension}, volume={65}, ISSN={["1573-2711"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85026840191&partnerID=MN8TOARS}, DOI={10.1007/s11249-017-0898-5}, number={3}, journal={TRIBOLOGY LETTERS}, author={Acharya, B. and Chestnut, M. and Marek, A. and Smirnov, A. I. and Krim, J.}, year={2017}, month={Sep} }
 @article{curtis_marek_smirnov_krim_2017, title={A comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively or negatively charged nanodiamonds}, volume={8}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85031433523&partnerID=MN8TOARS}, DOI={10.3762/bjnano.8.205}, abstractNote={This article reports a comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively (hydroxylated) or negatively (carboxylated) charged nanodiamonds (ND). Immersion in −ND suspensions resulted in a decrease in the macroscopic friction coefficients to values in the range 0.05–0.1 for both stainless steel and alumina, while +ND suspensions yielded an increase in friction for stainless steel contacts but little to no increase for alumina contacts. Quartz crystal microbalance (QCM), atomic force microscopy (AFM) and scanning electron microscopy (SEM) measurements were employed to assess nanoparticle uptake, surface polishing, and resistance to solid–liquid interfacial shear motion. The QCM studies revealed abrupt changes to the surfaces of both alumina and stainless steel upon injection of –ND into the surrounding water environment that are consistent with strong attachment of NDs and/or chemical changes to the surfaces. AFM images of the surfaces indicated slight increases in the surface roughness upon an exposure to both +ND and −ND suspensions. A suggested mechanism for these observations is that carboxylated −NDs from aqueous suspensions are forming robust lubricious deposits on stainless and alumina surfaces that enable gliding of the surfaces through the −ND suspensions with relatively low resistance to shear. In contrast, +ND suspensions are failing to improve tribological performance for either of the surfaces and may have abraded existing protective boundary layers in the case of stainless steel contacts. This study therefore reveals atomic scale details associated with systems that exhibit starkly different macroscale tribological properties, enabling future efforts to predict and design complex lubricant interfaces.}, number={1}, journal={Beilstein Journal of Nanotechnology}, author={Curtis, C.K. and Marek, A. and Smirnov, Alex I. and Krim, Jacqueline}, year={2017}, pages={2045–2059} }
 @article{curtis_marek_smirnov_krim_2017, title={A comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively or negatively charged nanodiamonds}, volume={8}, journal={Beilstein Journal of Nanotechnology}, author={Curtis, C. K. and Marek, A. and Smirnov, A. I. and Krim, J.}, year={2017}, pages={2045–2059} }
 @article{acharya_sidheswaran_yungk_krim_2017, title={Quartz crystal microbalance apparatus for study of viscous liquids at high temperatures}, volume={88}, ISSN={["1089-7623"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85013763853&partnerID=MN8TOARS}, DOI={10.1063/1.4976024}, abstractNote={A design for a Quartz Crystal Microbalance (QCM) setup for use with viscous liquids at temperatures of up to 300 °C is reported. The system response for iron and gold coated QCM crystals to two common lubricant base oils, polyalphaolefin and halocarbon, is reported, yielding results that are consistent with theoretical predictions that incorporate electrode nanoscale surface roughness into their analysis.}, number={2}, journal={REVIEW OF SCIENTIFIC INSTRUMENTS}, author={Acharya, Biplav and Sidheswaran, Meera A. and Yungk, Ronald and Krim, Jacqueline}, year={2017}, month={Feb} }
 @article{jafarabadi_marek_koolivand_acharya_nevzorov_krim_smirnov_2016, title={Interactions of Antibacterial Peptides with Nanotubular Lipid Bilayers: Binding Kinetics and Distortions of the Bilayer Structure}, volume={110}, ISSN={0006-3495}, url={http://dx.doi.org/10.1016/J.BPJ.2015.11.488}, DOI={10.1016/J.BPJ.2015.11.488}, abstractNote={Interactions of peptides with membranes are central for understanding key cellular processes involving membrane proteins such as folding, signaling, transport, energy conversion, and immune response. These interactions also determine efficiency of antibacterial and cytotoxic peptides in disrupting the barrier function of cellular membranes. We employed macroscopically aligned tubular lipid bilayers confined inside cylindrical nanopores of anodic aluminum oxide (AAO) as a versatile nanotechnology platform to study membrane interactions of antibacterial peptides of melittin and alamecitin. Kinetics of peptide binding to lipid nanotubes and the eventual lipid removal/lysis (for melittin) were observed by quartz crystal microbalance (QCM) using a crystal with an in-house fabricated nanostructured surface while the structural changes in bilayers were monitored by solid state oriented sample NMR. Specifically, using 78 nm nanopores we have achieved exceptionally narrow (100-140 Hz or <1 ppm) 31P resonances of the lipid phosphate groups of macroscopically aligned nanotubular bilayers that indicated <1-2o mosaic spread in the lipid alignment in the absence of bioreactive peptides. 31P resonances broadened and shifted towards the isotropic values upon interacting with melittin with some lysis of lipids observed after several hours of exposure. The binding and lipid lysis from bilayers confined in essentially the same nanopores albeit at much smaller lipid quantity were further quantified by real-time QCM for bilayers of various lipid compositions. Taken together, the data relate peptide binding and lysis kinetics to structural changes in lipid bilayers, thus, shedding the light on the underlying multistep mechanism. The main advantage of the lipid nanotube AAO platform is in its versatile applicability to various biophysical methods such QCM and NMR under essentially the same environmental conditions such as pH, ionic strength, temperature, etc. and exceptionally broad range of lipid bilayer compositions.}, number={3}, journal={Biophysical Journal}, publisher={Elsevier BV}, author={Jafarabadi, Morteza and Marek, Antonin and Koolivand, Amir and Acharya, Biplav and Nevzorov, Alexander A. and Krim, Jacqueline and Smirnov, Alex I.}, year={2016}, month={Feb}, pages={79a} }
 @article{liu_leininger_koolivand_smirnov_shenderova_brenner_krim_2015, title={Tribological properties of nanodiamonds in aqueous suspensions: effect of the surface charge}, volume={5}, ISSN={["2046-2069"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84942156290&partnerID=MN8TOARS}, DOI={10.1039/c5ra14151f}, abstractNote={The sign of nanodiamond surface charge is discovered to profoundly impact friction at both nanometer and macroscopic scales.}, number={96}, journal={RSC ADVANCES}, author={Liu, Zijian and Leininger, Dustin and Koolivand, Amir and Smirnov, Alex I. and Shenderova, Olga and Brenner, Donald W. and Krim, Jacqueline}, year={2015}, pages={78933–78940} }
 @inproceedings{brenner_mahbooba_saberi-movahed_krim_liu_ivanov_osawa_shenderova_2014, title={Nanodiamond-based nanolubricants: Experiment and modeling}, volume={1703}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84924359244&partnerID=MN8TOARS}, DOI={10.1557/opl.2014.840}, abstractNote={ABSTRACT}, booktitle={Materials Research Society Symposium Proceedings}, author={Brenner, D. and Mahbooba, Z. and Saberi-Movahed, F. and Krim, J. and Liu, Z. and Ivanov, M.G. and Osawa, E. and Shenderova, O.}, year={2014} }
 @article{pan_krim_2013, title={Scanning tunneling microscope-quartz crystal microbalance study of temperature gradients at an asperity contact}, volume={84}, ISSN={0034-6748 1089-7623}, url={http://dx.doi.org/10.1063/1.4767239}, DOI={10.1063/1.4767239}, abstractNote={Investigations of atomic-scale friction frequently involve setups where a tip and substrate are initially at different temperatures. The temperature of the sliding interface upon contact has thus become a topic of interest. A method for detecting initial tip-sample temperature differences at an asperity contact is described, which consists of a scanning tunneling microscope (STM) tip in contact with the surface electrode of a quartz crystal microbalance (QCM). The technique makes use of the fact that a QCM is extremely sensitive to abrupt changes in temperature. In order to demonstrate the technique's capabilities, QCM frequency shifts were recorded for varying initial tip-substrate temperature differences as an STM tip was brought into and out of contact. The results are interpreted within the context of a recent model for thermal heat conduction at an asperity contact, and it is concluded that the transient frequency response is attributable to small changes in temperature close to the region of contact rather than a change in the overall temperature of the QCM itself. For the assumed model parameters, the results moreover reveal substantial temperature discontinuities at the boundary between the tip and the sample, for example, on the order of 10–15 °C for initial temperature differences of 20 °C.}, number={1}, journal={Review of Scientific Instruments}, publisher={AIP Publishing}, author={Pan, L. and Krim, J.}, year={2013}, month={Jan}, pages={014901} }
 @misc{berman_krim_2013, title={Surface science, MEMS and NEMS: Progress and opportunities for surface science research performed on, or by, microdevices}, volume={88}, ISSN={["0079-6816"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84877058176&partnerID=MN8TOARS}, DOI={10.1016/j.progsurf.2013.03.001}, abstractNote={Micro- and Nano-Electro-Mechanical Systems (MEMS and NEMS) represent existing (MEMS) and emerging (NEMS) technologies based on microfabrication of micron to nanometer scale miniature mechanical components (gears, latches, mirrors, etc.) that are integrated with electrical elements to allow for electro-mechanical actuation and/or capacitive displacement detection. One common aspect of MEMS and NEMS devices is that they have mechanical functionality that may include moveable parts whose motion is controlled by external electrical connections. Current fabrication methods, along with high surface to volume ratios, make MEMS and NEMS devices highly susceptible to surface forces and adsorbed surface species, to the point where the devices are now being increasingly utilized as sensitive probes in fundamental surface science studies. This sensitivity can potentially be used to great advantage if the devices can be made to operate reproducibly in well controlled environments. This review highlights a number of such recent studies, beginning with an overview of the fabrication processes employed for silicon, metal, diamond, graphene and carbon nanotube – based device technologies. A discussion of how traditional surface science studies on passive two-dimensional substrates compare to and contrast with studies performed on, or by, MEMS and/or NEMS devices, is also included. The overall goal is to highlight areas of current opportunity for surface scientists in the flourishing arena of micro- and nano-device fabrication and technology.}, number={2}, journal={PROGRESS IN SURFACE SCIENCE}, author={Berman, D. and Krim, J.}, year={2013}, month={May}, pages={171–211} }
 @misc{krim_2012, title={Friction and energy dissipation mechanisms in adsorbed molecules and molecularly thin films}, volume={61}, ISSN={["1460-6976"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84864996533&partnerID=MN8TOARS}, DOI={10.1080/00018732.2012.706401}, abstractNote={This review provides an overview of recent advances that have been achieved in understanding the basic physics of friction and energy dissipation in molecularly thin adsorbed films and the associated impact on friction at microscopic and macroscopic length scales. Topics covered include a historical overview of the fundamental understanding of macroscopic friction, theoretical treatments of phononic and electronic energy dissipation mechanisms in thin films, and current experimental methods capable of probing such phenomena. Measurements performed on adsorbates sliding in unconfined geometries with the quartz crystal microbalance technique receive particular attention. The final sections review the experimental literature of how measurements of sliding friction in thin films reveal energy dissipation mechanisms and how the results can be linked to film-spreading behavior, lubrication, film phase transitions, superconductivity-dependent friction, and microelectromechanical systems applications. Materials systems reported on include adsorbed films comprised of helium, neon, argon, krypton, xenon, water, oxygen, nitrogen, carbon monoxide, ethane, ethanol, trifluoroethanol, methanol, cyclohexane, ethylene, pentanol, toluene, tricresylphosphate, t-butylphenyl phosphate, benzene, and iodobenzene. Substrates reported on include silver, gold, aluminum, copper, nickel, lead, silicon, graphite, graphene, fullerenes, C60, diamond, carbon, diamond-like carbon, and YBa2Cu3O7, and self-assembled monolayers consisting of tethered polymeric molecules.}, number={3}, journal={ADVANCES IN PHYSICS}, author={Krim, Jacqueline}, year={2012}, pages={155–323} }
 @article{walker_jaye_krim_cole_2012, title={Frictional temperature rise in a sliding physisorbed monolayer of Kr/graphene}, volume={24}, ISSN={0953-8984 1361-648X}, url={http://dx.doi.org/10.1088/0953-8984/24/42/424201}, DOI={10.1088/0953-8984/24/42/424201}, abstractNote={A quartz crystal microbalance (QCM) with a graphene/Ni(111) electrode has been used to probe frictional heating effects in Kr monolayers sliding on the microbalance electrode in response to its oscillatory motion. The temperatures of the sliding Kr monolayers are observed to rise approximately 13 K higher than their static counterparts, but show surprisingly little dependence on oscillation amplitude. Although counterintuitive, the observation can be explained by noting that the Kr surface residence times are limited, which effectively caps how much the temperature can rise.}, number={42}, journal={Journal of Physics: Condensed Matter}, publisher={IOP Publishing}, author={Walker, M and Jaye, C and Krim, J and Cole, Milton W}, year={2012}, month={Oct}, pages={424201} }
 @article{berman_krim_2012, title={Impact of oxygen and argon plasma exposure on the roughness of gold film surfaces}, volume={520}, ISSN={["0040-6090"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84863600648&partnerID=MN8TOARS}, DOI={10.1016/j.tsf.2012.06.033}, abstractNote={The impact of oxygen and argon plasma exposure on the roughness of gold film Quartz Crystal Microbalance (QCM) electrodes is reported here, employing low levels of gas uptake and scanning tunneling microscope measurements to probe the post-exposure surface morphology. For equal exposure times, argon plasma bombardment is observed to produce both greater material removal and greater change in surface roughness. A possible explanation for this is that the oxygen plasma produces a protective gold oxide layer, which may remove the contaminants from the surface without creating defects in the gold surface. The result is also consistent with prior reports of chemical cleaning of the surface by reactive oxygen ions. Pentane gas adsorption on the argon bombarded QCM surfaces was, moreover, observed to occur at pressures that are several orders of magnitude lower than that for an unbombarded surface.}, number={19}, journal={THIN SOLID FILMS}, author={Berman, D. and Krim, J.}, year={2012}, month={Jul}, pages={6201–6206} }
 @article{altfeder_krim_2012, title={Temperature dependence of nanoscale friction for Fe on YBCO}, volume={111}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.4717983}, DOI={10.1063/1.4717983}, abstractNote={A magnetic probe microscopy study of levitation and atomic-scale friction is reported for Fe on YBCO (Tc = 92.5 K) in the temperature range 65–293 K. Below Tc, the friction coefficient is constant and exhibits no correlation with the strength of superconducting levitation forces. Above Tc, the friction coefficient increases progressively, and nearly doubles between Tc and room temperature. The results are discussed within the context of the underlying atomic-scale electronic and phononic mechanisms that give rise to friction, and it is concluded that contact electrification and static electricity may play a significant role in the non-superconducting phase. Given that the properties of YBCO can be finely tuned, the results point the way to a variety of interesting studies of friction and superconductors.}, number={9}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Altfeder, Igor and Krim, Jacqueline}, year={2012}, month={May}, pages={094916} }
 @article{walker_berman_nordquist_krim_2011, title={Electrical Contact Resistance and Device Lifetime Measurements of Au-RuO2-Based RF MEMS Exposed to Hydrocarbons in Vacuum and Nitrogen Environments}, volume={44}, ISSN={["1573-2711"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855198941&partnerID=MN8TOARS}, DOI={10.1007/s11249-011-9849-8}, number={3}, journal={TRIBOLOGY LETTERS}, author={Walker, M. J. and Berman, D. and Nordquist, C. and Krim, J.}, year={2011}, month={Dec}, pages={305–314} }
 @article{berman_walker_nordquist_krim_2011, title={Impact of adsorbed organic monolayers on vacuum electron tunneling contributions to electrical resistance at an asperity contact}, volume={110}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.3664770}, DOI={10.1063/1.3664770}, abstractNote={Electrical contact resistance measurements are reported for RF micro-electromechanical switches situated within an ultrahigh vacuum system equipped with in situ oxygen plasma cleaning capabilities. Measurements were performed on fused (permanently adhered) switches with Au/Au contacts and functioning switches with Au/RuO2 contacts in both the presence and absence of adsorbed monolayers of pentane and dodecane. For switches adhered in the closed position, adsorption occurs only in regions external to direct contact. For functioning switches, however, it can occur either within or exterior to the contact. The data are analyzed within the framework of two distinct geometries, to explore how the presence of adsorbed molecules in regions close to the contact may impact vacuum tunneling contributions to the experimentally measured resistance: (1) The resistance associated with direct contact in parallel with a vacuum tunneling path, which upon uptake of the monolayer is replaced by the molecular resistance and (2) a series connection of the direct contact resistance with the molecular layer after adsorption occurs, with the vacuum tunneling path assumed to be negligible. In all cases, the experimental results quantitatively favor scenario (1), whereby uptake of the molecular layer effectively shuts down the vacuum tunneling path, in this case approximately 30 Ω in the absence of an adsorbed film. The methods described herein thus constitute a new and original approach to documenting vacuum tunneling levels in regions of close proximity.}, number={11}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Berman, D. and Walker, M. J. and Nordquist, C. D. and Krim, J.}, year={2011}, month={Dec}, pages={114307} }
 @article{yang_hoffmann_lichtenwalner_krim_kingon_2011, title={Resolution of the transfer direction of field-evaporated gold atoms for nanofabrication and microelectromechanical system applications}, volume={98}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.3545846}, DOI={10.1063/1.3545846}, abstractNote={Field evaporation is an important phenomenon utilized in probe-based nanofabrication as well as a potential factor in contact reliability of microelectromechanical system (MEMS) switches. Previous studies have left the issue of transfer direction unresolved on account of uncertainties associated with sample geometry effects. We report a resolution of the transfer direction employing techniques to study field-induced transfer in both MEMS switches and atomic force microscope configurations. The results suggest the formation of positive gold ions that are transferred in the direction of the electric field, and confirm field evaporation as a material transport mechanism in MEMS switches.}, number={4}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Yang, Z. and Hoffmann, S. and Lichtenwalner, D. J. and Krim, J. and Kingon, A. I.}, year={2011}, month={Jan}, pages={044102} }
 @article{krim_yu_behringer_2011, title={Stick-Slip and the Transition to Steady Sliding in a 2D Granular Medium and a Fixed Particle Lattice}, volume={168}, ISSN={["1420-9136"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84857517105&partnerID=MN8TOARS}, DOI={10.1007/s00024-011-0364-5}, number={12}, journal={PURE AND APPLIED GEOPHYSICS}, author={Krim, J. and Yu, Peidong and Behringer, R. P.}, year={2011}, month={Dec}, pages={2259–2275} }
 @article{miller_theodore_brukman_wahl_krim_2010, title={A Nano- to Macroscale Tribological Study of PFTS and TCP Lubricants for Si MEMS Applications}, volume={38}, ISSN={["1573-2711"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77952673357&partnerID=MN8TOARS}, DOI={10.1007/s11249-009-9573-9}, number={1}, journal={TRIBOLOGY LETTERS}, author={Miller, Brendan P. and Theodore, Nimel D. and Brukman, Matthew J. and Wahl, Kathryn J. and Krim, Jacqueline}, year={2010}, month={Apr}, pages={69–78} }
 @article{yang_lichtenwalner_morris_krim_kingon_2010, title={Contact degradation in hot/cold operation of direct contact micro-switches}, volume={20}, ISSN={0960-1317 1361-6439}, url={http://dx.doi.org/10.1088/0960-1317/20/10/105028}, DOI={10.1088/0960-1317/20/10/105028}, abstractNote={Degradation of gold contacts in micro-switches was studied under an extensive range of operation conditions including high-electric-field ac/dc hot switching, low-electric-field hot switching and cold switching. Tests were conducted in a unique experimental switching operation set-up. Gold micro-contacts were characterized by an atomic force microscope. It was found that a unique material transfer/distribution feature was correlated with specific switching operations. New insights into contact degradation mechanisms of micro-switches were achieved by analyzing contact degradation features under varied operation conditions. Our results indicate that for high-electric-field hot switching, gold atoms are transferred from the ‘anode’ contact to the ‘cathode’ contact via field evaporation; for low-electric-field hot switching, material transfer is induced by transient heat; and for cold switching, contact resistance can be jeopardized by surface contamination and surface roughness if contact force is low.}, number={10}, journal={Journal of Micromechanics and Microengineering}, publisher={IOP Publishing}, author={Yang, Z and Lichtenwalner, D and Morris, A and Krim, J and Kingon, A I}, year={2010}, month={Sep}, pages={105028} }
 @article{berman_walker_krim_2010, title={Contact voltage-induced softening of RF microelectromechanical system gold-on-gold contacts at cryogenic temperatures}, volume={108}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.3459893}, DOI={10.1063/1.3459893}, abstractNote={A series of experiments were performed in vacuum environments to investigate the impact of rf micromechanical system switch contact voltage versus resistance for gold-on-gold contacts at cryogenic temperatures. The purpose of this work was twofold as follows: (1) to examine whether asperity heating models already validated for high temperature contacts were also applicable at cryogenic temperatures and (2) to explore the implications and validity of prior suggestions that contact temperatures between 338 and 373 K are high enough to dissociate adsorbed film and/or push them aside but low enough to prevent asperities from becoming soft and adherent. Measurements on two distinct switch types, fabricated at independent laboratories, were performed in the temperature range 79–293 K and for contact voltages ranging from 0.01 to 0.13 V. Contact resistance values at all temperatures were observed to be lower for higher contact voltages, consistent with the aforementioned asperity heating models, whereby increased contact currents are associated with increased heating and softening effects. In situ removal of adsorbed species by oxygen plasma cleaning resulted in switch adhesive failure. Switches that had not been cleaned meanwhile exhibited distinct reductions in resistance at contact temperatures close to 338 K, consistent with suggestions that films begin to desorb, disassociate, and/or be pushed aside at that temperature.}, number={4}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Berman, D. and Walker, M. J. and Krim, J.}, year={2010}, month={Aug}, pages={044307} }
 @article{hook_ohlhausen_krim_dugger_2010, title={Evaluation of Oxygen Plasma and UV Ozone Methods for Cleaning of Occluded Areas in MEMS Devices}, volume={19}, ISSN={["1941-0158"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78649673539&partnerID=MN8TOARS}, DOI={10.1109/jmems.2010.2067193}, abstractNote={UV ozone and oxygen plasma treatments are two common procedures for cleaning silicon surfaces. The extent to which hidden surfaces of microelectromechanical systems (MEMS) are cleaned by these methods has not been well documented. To probe and compare the effectiveness of the two methods for cleaning occluded regions in MEMS, devices consisting of large movable flaps were fabricated to produce hidden surfaces whose occluded regions exceeded the aspect ratios that typically occur in MEMS devices. The gaps between the flap and the substrate in the custom flap devices were designed to be variable in extent. Their interior regions were initially coated with chemisorbed monolayers and then subjected to cleaning. Both techniques removed monolayers on exposed surfaces and both, to some extent, removed monolayers present on the occluded surfaces. Oxygen plasma was found to be a far more effective method for cleaning the occluded surfaces than the UV ozone method. However, in occlusions with exceptionally large aspect ratios of 1700 : 1, even oxygen plasma could not remove all traces of the chemisorbed monolayers.}, number={6}, journal={JOURNAL OF MICROELECTROMECHANICAL SYSTEMS}, author={Hook, D. Adam and Ohlhausen, James A. and Krim, Jacqueline and Dugger, Michael T.}, year={2010}, month={Dec}, pages={1292–1298} }
 @article{walker_nordquist_czaplewski_patrizi_mcgruer_krim_2010, title={Impact of in situ oxygen plasma cleaning on the resistance of Ru and Au-Ru based rf microelectromechanical system contacts in vacuum}, volume={107}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.3353991}, DOI={10.1063/1.3353991}, abstractNote={Contact resistance measurements are reported for radio frequency microelectromechanical system switches operating in an ultrahigh vacuum system equipped with in situ oxygen plasma cleaning capabilities. Ru-based contacts were prepared by means of standard sputtering techniques, sputtering followed by postdeposition oxidation, (surface RuO2) or reactive sputtering in the presence of oxygen (bulk RuO2). In situ oxygen plasma cleaning lowered the resistance of Ru contacts by two or more orders of magnitude but not lower than Au contacts, irrespective of whether the Au contacts were cleaned. The time dependence of the resistance was fit to power law extrapolations to infer contact creep properties and resistance values at t=∞. Time-dependent creep properties of mixed Au-Ru contacts were observed to be similar to those of Au-Au contacts, while the absolute value of the resistance of such contacts was more comparable to Ru-Ru contacts. Prior to, and for short oxygen plasma exposure times, bulk RuO2 resistance values exhibited much larger variations than values measured for surface RuO2. For O2 plasma exposure times exceeding about 5 min, the bulk and surface RuO2 resistance values converged, at both t=0 and t=∞, with the t=∞ values falling within experimental error of theoretical values predicted for ideal surfaces. The data strongly support prior reports in the surface science literature of oxygen plasma induced thickening of oxide layers present on Ru surfaces. In addition, they demonstrate that vacuum alone is insufficient to remove contaminants from the contact surfaces and/or prevent such contaminants from reforming after oxygen plasma exposure.}, number={8}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Walker, M. and Nordquist, C. and Czaplewski, D. and Patrizi, G. and McGruer, N. and Krim, J.}, year={2010}, month={Apr}, pages={084509} }
 @article{dunckle_altfeder_voevodin_jones_krim_taborek_2010, title={Temperature dependence of single-asperity friction for a diamond on diamondlike carbon interface}, volume={107}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.3436564}, DOI={10.1063/1.3436564}, abstractNote={A variable temperature, ultrahigh vacuum atomic force microscope (AFM) was used to characterize interfacial friction for a single-asperity diamond contact on a diamondlike carbon (DLC) substrate over a nominal substrate temperature range of 90 to 275 K. Calibrated friction force measurements were obtained by analyzing lateral force hysteresis loops as a function of normal force. For sufficiently large normal forces, the lateral force was proportional to the normal force, and a friction coefficient μ could be identified. μ varied approximately linearly with substrate temperature, with μ=0.28 at T=90 K and μ=0.38 at 275 K. These results are compared to other recent variable temperature AFM friction measurements and to theoretical calculations based on the Tomlinson model. This comparison is obscured by large, experimentally uncontrolled temperature differences between the tip and the substrate which inevitably exist in conventional, variable temperature AFMs. A thermal model which can be used to quantitatively estimate these temperature differences is presented.}, number={11}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Dunckle, C. G. and Altfeder, I. B. and Voevodin, A. A. and Jones, J. and Krim, J. and Taborek, P.}, year={2010}, month={Jun}, pages={114903} }
 @inproceedings{dawson_krim_2009, title={A combined scanning tunneling microscope-quartz crystal microbalance study of heating and wear at a sliding interface}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70349885443&partnerID=MN8TOARS}, booktitle={2008 Proceedings of the STLE/ASME International Joint Tribology Conference, IJTC 2008}, author={Dawson, B.D. and Krim, J.}, year={2009}, pages={61–63} }
 @article{yang_lichtenwalner_morris_krim_kingon_2009, title={Comparison of Au and Au-Ni Alloys as Contact Materials for MEMS Switches}, volume={18}, ISSN={["1941-0158"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-67349128609&partnerID=MN8TOARS}, DOI={10.1109/JMEMS.2008.2010850}, abstractNote={This paper reports on a comparison of gold and gold-nickel alloys as contact materials for microelectromechanical systems (MEMS) switches. Pure gold is commonly used as the contact material in low-force metal-contact MEMS switches. The top two failure mechanisms of these switches are wear and stiction, which may be related to the material softness and the relatively high surface adhesion, respectively. Alloying gold with another metal introduces new processing options to strengthen the material against wear and reduce surface adhesion. In this paper, the properties of Au-Ni alloys were investigated as the lower contact electrode was controlled by adjusting the nickel content and thermal processing conditions. A unique and efficient switching degradation test was conducted on the alloy samples, using pure gold upper microcontacts. Solid-solution Au-Ni samples showed reduced wear rate but increased contact resistance, while two-phase Au-Ni (20 at.% Ni) showed a substantial improvement of switching reliability with only a small increase of contact resistance. Discussion of the effects of phase separation, surface topography, hardness, and electrical resistivity on contact resistance and switch degradation is also included.}, number={2}, journal={JOURNAL OF MICROELECTROMECHANICAL SYSTEMS}, author={Yang, Zhenyin and Lichtenwalner, Daniel J. and Morris, Arthur S., III and Krim, Jacqueline and Kingon, Angus I.}, year={2009}, month={Apr}, pages={287–295} }
 @article{krim_behringer_2009, title={Friction, force chains, and falling fruit}, volume={62}, ISSN={0031-9228 1945-0699}, url={http://dx.doi.org/10.1063/1.3226776}, DOI={10.1063/1.3226776}, abstractNote={Why is it that stacked apples seem so stable, but removing the “wrong” apple can cause the whole pile to tumble down?}, number={9}, journal={Physics Today}, publisher={AIP Publishing}, author={Krim, Jacqueline and Behringer, Robert P.}, year={2009}, month={Sep}, pages={66–67} }
 @article{altfeder_hu_voevodin_krim_2009, title={Magic-Sized Diamond Nanocrystals}, volume={102}, ISSN={["1079-7114"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-64649084727&partnerID=MN8TOARS}, DOI={10.1103/physrevlett.102.136104}, abstractNote={The 2D structural transformation of a heavily boron-doped diamond surface has been revealed using scanning tunneling microscopy (STM). We found that at boron densities above the metal-insulator transition the diamond surface is comprised of spatially ordered magic-sized nanocrystals. The development of quantized electron gas inside these nanocrystals is directly confirmed by STM observation of standing electron waves. The experimental comparison of metallic and insulating diamond reveals the existence of the Fermi-sea-induced quantum selection rules for the self-assembly of nanostructures.}, number={13}, journal={PHYSICAL REVIEW LETTERS}, author={Altfeder, I. B. and Hu, J. J. and Voevodin, A. A. and Krim, J.}, year={2009}, month={Apr} }
 @inproceedings{pan_dawson_krim_baker_pearson_zikry_vovoedin_2009, title={Nanoscale design of adaptive tribological coatings}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70349869620&partnerID=MN8TOARS}, booktitle={2008 Proceedings of the STLE/ASME International Joint Tribology Conference, IJTC 2008}, author={Pan, L. and Dawson, B. and Krim, J. and Baker, C. and Pearson, J. and Zikry, M. and Vovoedin, A.}, year={2009}, pages={65–67} }
 @article{krim_dawson_barefoot_pan_pearson_zikry_baker_voevodin_2009, title={Nanoscale design of adaptive tribological coatings for gold-ytrium based nanocomposites}, volume={3}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77749339040&partnerID=MN8TOARS}, DOI={10.1179/175158309X12586382418373}, abstractNote={Nanocomposites hold great promise for space and ambient applications on account of their ability to adapt to and exhibit low friction and wear rates in constantly varying environmental conditions. In order to explore the impact of nanocrystalline grain size and fractal scaling properties on tribological performance, the authors have performed experimental and theoretical studies examining nanotribological properties of gold–ytrium based nanocomposites. These include modelling the impact of grain size on film stress and wear attributes and the documentation of surface region grain size distributions. The authors’ modelling results associate smaller grain sizes with lower wear, consistent with experimental observations for the range of grain sizes studied. The findings show promise for nanoscale customisation of coatings so as to tailor them at the nanoscale in an application specific manner.}, number={4}, journal={Tribology - Materials, Surfaces and Interfaces}, author={Krim, J. and Dawson, B.D. and Barefoot, K. and Pan, L. and Pearson, J. and Zikry, M. and Baker, C. and Voevodin, A.}, year={2009}, pages={145–150} }
 @article{miller_krim_2009, title={Sliding Friction Measurements of Molecularly Thin Ethanol and Pentanol Films: How Friction and Spreading Impact Lubricity}, volume={157}, ISSN={["1573-7357"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70349678704&partnerID=MN8TOARS}, DOI={10.1007/s10909-009-9915-x}, number={3-4}, journal={JOURNAL OF LOW TEMPERATURE PHYSICS}, author={Miller, Brendan P. and Krim, Jacqueline}, year={2009}, month={Nov}, pages={252–267} }
 @article{brown_rezvanian_zikry_krim_2009, title={Temperature dependence of asperity contact and contact resistance in gold RF MEMS switches}, volume={19}, ISSN={0960-1317 1361-6439}, url={http://dx.doi.org/10.1088/0960-1317/19/2/025006}, DOI={10.1088/0960-1317/19/2/025006}, abstractNote={Experimental measurements and modeling predictions were obtained to characterize the electro-mechanical response of two different gold contact radio frequency microelectromechanical system (RF MEMS) switches due to variations in the temperature and applied contact voltage. A three-dimensional surface roughness profile from AFM measurements of the top contact surface of a sample RF MEMS switch was used to obtain modeling predictions of the time-dependent deformation of the asperity microcontacts, real areas of contact, number of asperity microcontacts and constriction resistance. The experimental data indicated a decrease in the overall resistance and a decrease in the creep mechanism at 77 K and 5.6 K when compared to measurements at 293 K. At 293 K, there is more contact area per unit time, and the resistance drop from the increase in real contact area dominates the resistance increase due to asperity heating. At 77 K, the creep rate is reduced, and fewer asperities are in contact. At 5.6 K, the change in contact area over time is small, and the contact resistance measurement is dominated by the Joule heating. The data presented and constriction resistance modeling for gold RF MEMS switches show that temperature plays a significant role in the creep deformation and heating of switch contacts.}, number={2}, journal={Journal of Micromechanics and Microengineering}, publisher={IOP Publishing}, author={Brown, C and Rezvanian, O and Zikry, M A and Krim, J}, year={2009}, month={Jan}, pages={025006} }
 @article{dawson_lee_krim_2009, title={Tribo-Induced Melting Transition at a Sliding Asperity Contact}, volume={103}, ISSN={["0031-9007"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70450230497&partnerID=MN8TOARS}, DOI={10.1103/physrevlett.103.205502}, abstractNote={Observation of a tribo-induced transition from solid to liquidlike behavior is reported for a scanning tunneling microscope tip in sliding contact with an indium electrode of a quartz crystal microbalance (QCM). In particular, at a sufficiently high asperity sliding speed (about 1 m/s) and/or sample temperature, a change in the contact mechanics is observed that is consistent with melting in terms of both the QCM response and an energy analysis. The results confirm that the surface, rather than bulk, melting point temperature is the more relevant quantity for tribological considerations.}, number={20}, journal={PHYSICAL REVIEW LETTERS}, author={Dawson, B. D. and Lee, S. M. and Krim, J.}, year={2009}, month={Nov} }
 @article{brown_morris_kingon_krim_2008, title={Cryogenic Performance of RF MEMS Switch Contacts}, volume={17}, ISSN={["1941-0158"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-57449110516&partnerID=MN8TOARS}, DOI={10.1109/JMEMS.2008.2005328}, abstractNote={A series of experiments was performed to characterize RF microelectromechanical system switch performance under variable environmental conditions and cryogenic temperatures. Data were recorded in helium and nitrogen environments to lower stiction failure rates as well as to circumvent switch bouncing arising from low pressure at cryogenic temperatures. Contact resistance values were observed to be lower at cryogenic temperatures but still two orders of magnitude higher than the values predicted for the constriction resistance of gold asperity contacts, consistent with the presence of adsorbed films on the contacts. An asperity-heating model was applied, from which it was deduced that contact voltages can selectively disassociate adsorbed films from the contact surface while not softening the gold asperity contacts. The results are consistent with the reduced mobility of the adsorbed surface films at cryogenic temperatures.}, number={6}, journal={JOURNAL OF MICROELECTROMECHANICAL SYSTEMS}, author={Brown, Chris and Morris, Arthur S., III and Kingon, Angus I. and Krim, Jacqueline}, year={2008}, month={Dec}, pages={1460–1467} }
 @article{trasca_cole_coffey_krim_2008, title={Gas adsorption on a C-60 monolayer}, volume={77}, ISSN={["1550-2376"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-42449113449&partnerID=MN8TOARS}, DOI={10.1103/physreve.77.041603}, abstractNote={The adsorption geometry of various gases on top of a C60 monolayer is investigated. The potential energy experienced by an adsorbate atom in the vicinity of a C60 molecule consists of Lennard-Jones interactions integrated over the spherical surface of the molecule. The adsorption potential exhibits strongly attractive sites which lead to a commensurate phase. The next adsorption sites are assumed on the basis of the symmetries of the triangular C60 array. The competition between different adsorption phases is solved by energy minimization. The onset pressure of each phase is computed and compared with experimental data for Kr on top of a C60 monolayer.}, number={4}, journal={PHYSICAL REVIEW E}, author={Trasca, R. A. and Cole, M. W. and Coffey, T. and Krim, J.}, year={2008}, month={Apr} }
 @inproceedings{rezvanian_zikry_brown_krim_2008, title={RF MEMS behavior, surface roughness and asperity contact}, volume={1052}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-45849129829&partnerID=MN8TOARS}, booktitle={Materials Research Society Symposium Proceedings}, author={Rezvanian, O. and Zikry, M.A. and Brown, C. and Krim, J.}, year={2008}, pages={135–140} }
 @article{rezvanian_brown_zikry_kingon_krim_irving_brenner_2008, title={The role of creep in the time-dependent resistance of Ohmic gold contacts in radio frequency microelectromechanical system devices}, volume={104}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.2953072}, DOI={10.1063/1.2953072}, abstractNote={It is shown that measured and calculated time-dependent electrical resistances of closed gold Ohmic switches in radio frequency microelectromechanical system (rf-MEMS) devices are well described by a power law that can be derived from a single asperity creep model. The analysis reveals that the exponent and prefactor in the power law arise, respectively, from the coefficient relating creep rate to applied stress and the initial surface roughness. The analysis also shows that resistance plateaus are not, in fact, limiting resistances but rather result from the small coefficient in the power law. The model predicts that it will take a longer time for the contact resistance to attain a power law relation with each successive closing of the switch due to asperity blunting. Analysis of the first few seconds of the measured resistance for three successive openings and closings of one of the MEMS devices supports this prediction. This work thus provides guidance toward the rational design of Ohmic contacts with enhanced reliabilities by better defining variables that can be controlled through material selection, interface processing, and switch operation.}, number={2}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Rezvanian, O. and Brown, C. and Zikry, M. A. and Kingon, A. I. and Krim, J. and Irving, D. L. and Brenner, D. W.}, year={2008}, month={Jul}, pages={024513} }
 @article{hook_timpe_dugger_krim_2008, title={Tribological degradation of fluorocarbon coated silicon microdevice surfaces in normal and sliding contact}, volume={104}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.2960567}, DOI={10.1063/1.2960567}, abstractNote={Reported here is a study of the tribological degradation of the contact interface of a fluorocarbon monolayer-coated polycrystalline silicon microdevice. A surface micromachined silicon tribometer is employed to track changes in the adhesion and friction properties during repetitive normal and sliding contacts. Evidence for tribological degradation commences immediately for parallel sliding contact motion, and is slightly delayed in the case of repetitive impact loading normal to the surface. The observed changes in interfacial behavior indicate dramatic changes in the chemical (i.e., surface energy) and physical (i.e., roughness, real contact area, etc.) nature of the contacting surfaces. Results from microscale sliding and impact experiments are interpreted in the light of the primary physical and chemical degradation mechanisms of monolayer-coated silicon microdevices.}, number={3}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Hook, D. Adam and Timpe, Shannon J. and Dugger, Michael T. and Krim, Jacqueline}, year={2008}, month={Aug}, pages={034303} }
 @article{yang_lichtenwalner_morris_menzel_nauenheim_gruverman_krim_kingon_2007, title={A new test facility for efficient evaluation of MEMS contact materials}, volume={17}, ISSN={["1361-6439"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-51649090154&partnerID=MN8TOARS}, DOI={10.1088/0960-1317/17/9/006}, abstractNote={A novel test facility for the efficient evaluation of microelectromechanical system (MEMS) switches and the development of alternative contact materials is described. The facility utilizes the upper cantilever from commercial MEMS contact switches, and tests these against alternative bottom contact materials within a modified atomic force microscope (AFM). The test closely approximates the real switch, but can accommodate a wider range of test conditions and contact materials. The facility allows alternative contact materials to be easily and quickly incorporated, and therefore evaluated by measuring the number of cycles to failure. The evolution of the wear surfaces of the switch contact materials under test can also be easily examined. In order to demonstrate the facility, the evolution of the contact resistance and wear of a commercial RF MEMS cantilever with Au contacts was monitored under accelerated test conditions, comparing the behavior of Au bottom contacts to an alternative Au–Ni alloy contact material. The Au–Ni (20 at.%) alloy displayed reduced wear rates and improved switch cycle lifetimes compared to pure Au, while retaining acceptable values of contact resistance.}, number={9}, journal={JOURNAL OF MICROMECHANICS AND MICROENGINEERING}, author={Yang, Z. and Lichtenwalner, D. and Morris, A. and Menzel, S. and Nauenheim, C. and Gruverman, A. and Krim, J. and Kingon, A. I.}, year={2007}, month={Sep}, pages={1788–1795} }
 @article{neeyakorn_varma_jaye_burnette_lee_nemanich_grant_krim_2007, title={Dynamics of vapor-phase organophosphates on silicon and OTS}, volume={27}, ISSN={["1573-2711"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34547211720&partnerID=MN8TOARS}, DOI={10.1007/s11249-007-9224-y}, number={3}, journal={TRIBOLOGY LETTERS}, author={Neeyakorn, Worakarn and Varma, Manju and Jaye, Cherno and Burnette, James E. and Lee, Sang M. and Nemanich, Robert J. and Grant, Christine S. and Krim, Jacqueline}, year={2007}, month={Sep}, pages={269–276} }
 @article{brenner_irving_kingon_krim_padgett_2007, title={Multiscale analysis of liquid lubrication trends from industrial machines to micro-electrical-mechanical systems}, volume={23}, ISSN={["0743-7463"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34548529657&partnerID=MN8TOARS}, DOI={10.1021/la701280k}, abstractNote={An analytic multiscale expression is derived that yields conditions for effective liquid lubrication of oscillating contacts via surface flow over multiple time and length scales. The expression is a logistics function that depends on two quantities, the fraction of lubricant removed at each contact and a scaling parameter given by the logarithm of the ratio of the contact area to the product of the lubricant diffusion coefficient and the cycle time. For industrial machines the expression confirms the need for an oil mist. For magnetic disk drives, the expression predicts that existing lubricants are sufficient for next-generation data storage. For micro-electrical-mechanical systems, the expression predicts that a bound + mobile lubricant composed of tricresyl phosphate on an octadecyltrichlorosilane self-assembled monolayer will be effective only for temperatures greater than approximately 200 K and up to approximately MHz oscillation frequencies.}, number={18}, journal={LANGMUIR}, author={Brenner, D.W. and Irving, D.L. and Kingon, A.I. and Krim, Jacqueline and Padgett, C.W.}, year={2007}, month={Aug}, pages={9253–9257} }
 @misc{krim_2007, title={QCM tribology studies of thin adsorbed films}, volume={2}, ISSN={["1878-044X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34748914567&partnerID=MN8TOARS}, DOI={10.1016/s1748-0132(07)70142-1}, abstractNote={The ability to predict sliding friction in an adsorbed film system is key to a vast range of fundamental and applied issues in physics and nanotechnology. Sliding friction levels in molecularly thin layers can be measured experimentally by means of the quartz crystal microbalance (QCM) technique, which is readily comparable to theory, including both analytic calculations and molecular dynamics simulations. Progress in this area is summarized here, focusing on fundamental energy dissipation mechanisms and how nanoscale observations might be linked to the macroscopic world.}, number={5}, journal={NANO TODAY}, author={Krim, Jacqueline}, year={2007}, month={Oct}, pages={38–43} }
 @article{rezvanian_zikry_brown_krim_2007, title={Surface roughness, asperity contact and gold RFMEMS switch behavior}, volume={17}, ISSN={["1361-6439"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34748865043&partnerID=MN8TOARS}, DOI={10.1088/0960-1317/17/10/012}, abstractNote={Modeling predictions and experimental measurements were obtained to characterize the electro-mechanical response of radio frequency (RF) microelectromechanical (MEM) switches due to variations in surface roughness and finite asperity deformations. Three-dimensional surface roughness profiles were generated, based on a Weierstrass–Mandelbrot fractal representation, to match the measured roughness characteristics of contact bumps of manufactured RF MEMS switches. Contact asperity deformations due to applied contact pressures were then obtained by a creep constitutive formulation. The contact pressure is derived from the interrelated effects of roughness characteristics, material hardening and softening, temperature increases due to Joule heating and contact forces. This modeling framework was used to understand how contact resistance evolves due to changes in the real contact area, the number of asperities in contact, and the temperature and resistivity profiles at the contact points. The numerical predictions were qualitatively consistent with the experimental measurements and observations of how contact resistance evolves as a function of deformation time history. This study provides a framework that is based on integrated modeling and experimental measurements, which can be used in the design of reliable RF MEMS devices with extended life cycles.}, number={10}, journal={JOURNAL OF MICROMECHANICS AND MICROENGINEERING}, author={Rezvanian, O. and Zikry, M. A. and Brown, C. and Krim, J.}, year={2007}, month={Oct}, pages={2006–2015} }
 @article{coffey_krim_2006, title={C-60 molecular bearings and the phenomenon of nanomapping}, volume={96}, ISSN={["0031-9007"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33646544386&partnerID=MN8TOARS}, DOI={10.1103/physrevlett.96.186104}, abstractNote={Inspired by suggestions of C(60) "nanobearings," we have measured sliding friction on fixed and rotating C(60) layers to explore whether a lubricating effect is present. We refer to this general phenomenon as "nanomapping," whereby macroscopic attributes are mapped in a one on one fashion to nanoscale entities. Our measurements are the first to directly link friction to a documented molecular rotation state. Friction is, however, observed to be higher for rotating layers, in defiance of the ball-bearing analogy. Thus, no direct mapping of macro- to nanoscale attributes can be established.}, number={18}, journal={PHYSICAL REVIEW LETTERS}, author={Coffey, T and Krim, J}, year={2006}, month={May} }
 @article{abdelmaksoud_lee_padgett_irving_brenner_krim_2006, title={STM, QCM, and the windshield wiper effect: A joint theoretical-experimental study of adsorbate mobility and lubrication at high sliding rates}, volume={22}, ISSN={["0743-7463"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34247572834&partnerID=MN8TOARS}, DOI={10.1021/la061797w}, abstractNote={We have observed that when mobile adsorbed films of benzene, tricresyl phosphate, and tertiary-butyl phenyl phosphate are present on the surface electrode of a quartz crystal microbalance (QCM), oscillation of the QCM produces clearer scanning tunneling microscope (STM) images of the electrode surface. This is in contrast to an immobile overlayer of iodobenzene, where oscillation of the QCM does not affect image quality. This observation is attributed to a "windshield wiper effect", where at MHz frequencies the tip motion maintains a region of the surface where the absorbate concentration is reduced, which leads to a clearer image. A straightforward model is presented that supports this conclusion and that provides guidelines for effective lubrication of contacts operating at MHz frequencies.}, number={23}, journal={LANGMUIR}, author={Abdelmaksoud, M. and Lee, S. M. and Padgett, C. W. and Irving, D. L. and Brenner, D. W. and Krim, J.}, year={2006}, month={Nov}, pages={9606–9609} }
 @article{highland_krim_2006, title={Superconductivity dependent friction of water, nitrogen, and superheated he films adsorbed on Pb(111)}, volume={96}, ISSN={["1079-7114"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33745044222&partnerID=MN8TOARS}, DOI={10.1103/physrevlett.96.226107}, abstractNote={We report a quartz crystal microbalance study of sliding friction levels in N2, H2O, and superheated He films adsorbed on Pb(111) substrates alternating in and out of the superconducting state. Reductions in friction upon entry into the superconducting state are greater for N2 than He, consistent with a recent theory that linked electronic friction to adsorbate polarizability. Our work also reveals that repetitive cycling of an externally applied magnetic field may impact friction.}, number={22}, journal={PHYSICAL REVIEW LETTERS}, author={Highland, M. and Krim, J.}, year={2006}, month={Jun} }
 @inproceedings{hook_neeyakorn_krim_dugger_2005, title={A study of the tribological properties of bound plus mobile phase lubricants with QCM and mems sidewall tribometer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33644836879&partnerID=MN8TOARS}, booktitle={Proceedings of the World Tribology Congress III - WTC 2005}, author={Hook, A. and Neeyakorn, W. and Krim, J. and Dugger, M.T.}, year={2005}, pages={777–778} }
 @inproceedings{brown_krim_morris_2005, title={Analysis of cycle lifetimes and failure modes for RF MEMS switches}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-32844471244&partnerID=MN8TOARS}, booktitle={Proceedings of the World Tribology Congress III - 2005}, author={Brown, C. and Krim, J. and Morris, A.}, year={2005}, pages={343–344} }
 @book{bender_krim_2005, title={Applications of the piezoelectric quartz crystal microbalance for microdevice development}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891386722&partnerID=MN8TOARS}, DOI={10.1007/3-540-26449-3_6}, journal={Microscale Diagnostic Techniques}, author={Bender, J.W. and Krim, J.}, year={2005}, pages={227–259} }
 @article{krim_2005, title={Friction at the nano-scale}, volume={18}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-13444263593&partnerID=MN8TOARS}, DOI={10.1088/2058-7058/18/2/39}, abstractNote={IN THE scramble to revolutionize the world with nanotechnology we must not ignore friction. Nano-scale devices based on moving molecular components have the potential to radically alter technologies such as energy storage, drug delivery, computing, communications and chemical manufacture. But getting these devices from the laboratory to the marketplace is far from guaranteed.}, number={2}, journal={Physics World}, author={Krim, Jacqueline}, year={2005}, pages={31–34} }
 @article{coffey_krim_2005, title={Impact of substrate corrugation on the sliding friction levels of adsorbed films}, volume={95}, ISSN={["0031-9007"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-27144466341&partnerID=MN8TOARS}, DOI={10.1103/physrevlett.95.076101}, abstractNote={We report a quartz crystal microbalance (QCM) study of sliding friction for solid xenon monolayers at 77 K on Cu(111), Ni(111), graphene/Ni(111), and C(60) substrates. Simulations have predicted a strong dependence of phononic friction coefficient (eta) on surface corrugation in systems with similar lattice spacing, eta approximately U(2)(0), but this has never before been shown experimentally. In order to make direct comparisons with theory, substrates with similar lattice spacing but varying amplitudes of surface corrugation were studied. QCM data reveal friction levels proportional to U(2)(0), validating current theoretical and numerical predictions. Measurements of Xe/C(60) are also included for comparison purposes.}, number={7}, journal={PHYSICAL REVIEW LETTERS}, author={Coffey, T and Krim, J}, year={2005}, month={Aug} }
 @inproceedings{lee_abdelmaksoud_krim_2005, title={Nano-scale tribology study of organic adlayer-metal interface using quartz crystal microbalance combined with scanning tunneling microscopy}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33144489253&partnerID=MN8TOARS}, booktitle={Proceedings of the World Tribology Congress III - 2005}, author={Lee, S.M. and Abdelmaksoud, M. and Krim, J.}, year={2005}, pages={791–792} }
 @inproceedings{weeyakorn_lee_parker_burnette_bilbro_nemanich_krim_2005, title={Nanodynamics of vapor-phase organophosphates on silicon and OTS for lubrication purposes}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33144463024&partnerID=MN8TOARS}, booktitle={Proceedings of the World Tribology Congress III - 2005}, author={Weeyakorn, W. and Lee, S.M. and Parker, O. and Burnette, J.E. and Bilbro, L.S. and Nemanich, R.J. and Krim, J.}, year={2005}, pages={793–794} }
 @article{hussain_krim_grant_2005, title={OTS adsorption: A dynamic QCM study}, volume={262}, ISSN={["1873-4359"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-22144447874&partnerID=MN8TOARS}, DOI={10.1016/j.colsurfa.2005.03.016}, abstractNote={The uptake of octadecyltrichlorosilane (OTS) from an organic solution has been studied in situ and in real time by means of a quartz crystal microbalance (QCM) technique. Changes in both QCM frequency and resistance are reported for a range of OTS concentrations. In addition, the time dependence of OTS uptake has been used to calculate reaction constants. Silicon surfaces overall are characterized by higher levels of material uptake than gold.}, number={1-3}, journal={COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS}, author={Hussain, Y and Krim, J and Grant, C}, year={2005}, month={Jul}, pages={81–86} }
 @inproceedings{krim_2005, title={QCM studies of phononic and electronic contributions to sliding friction in adsorbed monolayers}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33144464455&partnerID=MN8TOARS}, booktitle={Proceedings of the World Tribology Congress III - 2005}, author={Krim, J.}, year={2005}, pages={489–490} }
 @article{coffey_krim_2005, title={Quartz-crystal microbalance studies of the slippage of solid and liquid krypton monolayers on metal(111) and C-60 surfaces}, volume={72}, ISSN={["1098-0121"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-29744434911&partnerID=MN8TOARS}, DOI={10.1103/physrevb.72.235414}, abstractNote={We report a quartz-crystal microbalance (QCM) study of the nanotribology of solid and liquid krypton monolayers adsorbed on Cu(111), Ag(111), Ni(111), and ${\mathrm{C}}_{60}$ substrates at $77.4\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. We document the liquid-solid phase transition and compare the slip times of the krypton for the various substrates. The slip times for the solid krypton monolayers are longer than the slip times for liquid krypton monolayers on metal substrates and monolayer ${\mathrm{C}}_{60}$ films, as observed previously for krypton/Au(111). However, for bilayer ${\mathrm{C}}_{60}$ films, the jump in slip time at the liquid-solid phase transition is absent. We discuss the data within the context of recent molecular dynamics simulations and suggest several potential explanations for the experimental observations.}, number={23}, journal={PHYSICAL REVIEW B}, author={Coffey, T and Krim, J}, year={2005}, month={Dec} }
 @article{lee_krim_2005, title={Scanning tunneling microscopy characterization of the surface morphology of copper films grown on mica and quartz}, volume={489}, ISSN={["0040-6090"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-23244457426&partnerID=MN8TOARS}, DOI={10.1016/j.tsf.2005.05.014}, abstractNote={The morphology of copper films grown on quartz, mica, and Ti/quartz has been investigated by means of scanning tunneling microscopy (STM). Films grown on quartz, both bare and pre-plated with titanium, are characterized by self-affine fractal scaling behavior over the length scale of 10∼500 nm, while films grown on mica are not. Annealing of the films to 340 °C reduces the root-mean-square (RMS) roughness values, despite the overall scaling behavior remains the same. Films grown on bare quartz have significantly larger RMS roughness than those grown on mica, or quartz pre-plated with titanium. For the latter two cases, the RMS roughness is very low, 1–4 nm for the length scale of L = 500 nm. The overall dependence of copper film morphology on various substrates were discussed in terms of interfacial reaction, lattice mismatch, and surface energy difference of interface surfaces.}, number={1-2}, journal={THIN SOLID FILMS}, author={Lee, SM and Krim, J}, year={2005}, month={Oct}, pages={325–329} }
 @article{abdelmaksoud_bender_krim_2004, title={Bridging the gap between macro- and nanotribology: A quartz crystal microbalance study of tricresylphosphate uptake on metal and oxide surfaces}, volume={92}, ISSN={["1079-7114"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-2942601925&partnerID=MN8TOARS}, DOI={10.1103/physrevlett.92.176101}, abstractNote={We report a quartz crystal microbalance study of the nanodynamical properties of tricresylphosphate (TCP) reaction films formed on high purity Fe, Cr, Fe oxide, and Cr oxide surfaces at elevated temperatures. The data reveal trace levels of interfacial slippage, potentially in conjunction with viscoelastic effects, for reaction films characterized by very low macroscopic friction coefficients. In contrast, rigidly attached TCP reaction films are observed in systems characterized by high macroscopic friction coefficients.}, number={17}, journal={PHYSICAL REVIEW LETTERS}, author={Abdelmaksoud, M and Bender, JW and Krim, J}, year={2004}, month={Apr} }
 @article{abdelmaksoud_bender_krim_2002, title={Nanotribology of a vapor-phase lubricant: A quartz crystal microbalance study of tricresylphosphate (TCP) uptake on iron and chromium}, volume={13}, ISSN={["1573-2711"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-2942624398&partnerID=MN8TOARS}, DOI={10.1023/A:1020155925183}, number={3}, journal={TRIBOLOGY LETTERS}, author={Abdelmaksoud, M and Bender, JW and Krim, J}, year={2002}, month={Oct}, pages={179–186} }
 @article{krim_2002, title={Resource Letter: FMMLS-1: Friction at macroscopic and microscopic length scales}, volume={70}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85024818749&partnerID=MN8TOARS}, DOI={10.1119/1.1484153}, abstractNote={This Resource Letter provides a guide to the literature on the fundamental origins of friction. Books, reviews, and journal articles are cited for the following topics: History of friction and tribology, the adhesion theory of macroscopic friction, first principles’ treatments of frictional energy dissipation at the atomic level, experimental methods for studying friction at the atomic-scale, stick-slip phenomena and lattice commensurability effects.}, number={9}, journal={American Journal of Physics}, author={Krim, J.}, year={2002}, pages={890–897} }
 @article{krim_2002, title={Surface science and the atomic-scale origins of friction: what once was old is new again}, volume={500}, ISSN={["1879-2758"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0037051006&partnerID=MN8TOARS}, DOI={10.1016/S0039-6028(01)01529-1}, abstractNote={Long neglected by physicists, the study of friction's atomic-level origins, or nanotribology, indicates that sliding friction stems from various unexpected sources, including sound energy, and static friction may arise from physisorbed molecules. Progress in this field will be discussed, with an emphasis on how the field of surface science has influenced our understanding of friction.}, number={1-3}, journal={SURFACE SCIENCE}, author={Krim, J}, year={2002}, month={Mar}, pages={741–758} }
 @article{coffey_abdelmaksoud_krim_2001, title={A scanning probe and quartz crystal microbalance study of the impact of C-60 on friction at solid-liquid interfaces}, volume={13}, ISSN={["0953-8984"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0035962962&partnerID=MN8TOARS}, DOI={10.1088/0953-8984/13/21/323}, abstractNote={We have investigated the changes in interfacial friction of toluene on mica and Ag(111) both in the presence and in the absence of interfacial C60 layers employing atomic force microscope (AFM) and quartz crystal microbalance (QCM) techniques. The lateral force measurements fail to detect C60 at the toluene/mica interface, presumably because the C60 is dislodged by the slow-moving probe tip. In contrast, QCM measurements of interfacial friction and slippage for toluene/Ag(111) are sensitive to the presence of interfacial C60. We see the friction double when C60 is present. The results are discussed in the light of the full-slip boundary condition which had been previously reported for surface forces apparatus (SFA) measurements on toluene/mica in the presence and absence of interfacial C60.}, number={21}, journal={JOURNAL OF PHYSICS-CONDENSED MATTER}, author={Coffey, T and Abdelmaksoud, M and Krim, J}, year={2001}, month={May}, pages={4991–4999} }
 @article{borovsky_krim_syed asif_wahl_2001, title={Measuring nanomechanical properties of a dynamic contact using an indenter probe and quartz crystal microbalance}, volume={90}, ISSN={["0021-8979"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0035894080&partnerID=MN8TOARS}, DOI={10.1063/1.1413493}, abstractNote={A study of the contact mechanics of a probe tip interacting with a quartz crystal microbalance (QCM) has been performed, involving simultaneous measurements of normal load, displacement, and contact stiffness with changes in QCM resonant frequency. For metal–metal and glass–metal contacts in air, the QCM frequency shifts were observed to be positive, and directly proportional to the contact area as inferred from the contact stiffness. Interfacial characteristics of the probe–tip contact (elasticity, contact size, and an estimate of the number of contacting asperities) were deduced by extending a prior model of single asperity contact to the case of multiple contacts. The extended model clarifies a number of seemingly disparate experimental results that have been reported in the literature.}, number={12}, journal={JOURNAL OF APPLIED PHYSICS}, author={Borovsky, B and Krim, J and Syed Asif, SA and Wahl, KJ}, year={2001}, month={Dec}, pages={6391–6396} }
 @article{mason_winder_krim_2001, title={On the current status of quartz crystal microbalance studies of superconductivity-dependent sliding friction}, volume={10}, ISSN={["1023-8883"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0008051478&partnerID=MN8TOARS}, DOI={10.1023/A:1009042816366}, number={1-2}, journal={TRIBOLOGY LETTERS}, author={Mason, BL and Winder, SM and Krim, J}, year={2001}, pages={59–65} }
 @article{majumder_mcgruer_adams_zavracky_morrison_krim_2001, title={Study of contacts in an electrostatically actuated microswitch}, volume={93}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0035948942&partnerID=MN8TOARS}, DOI={10.1016/S0924-4247(01)00627-6}, abstractNote={Surface micromachined, electrostatically actuated microswitches have been developed at Northeastern University. Microswitches with gold contacts typically have an initial contact resistance of the order of 0.1 Ω over the first 105 cycles of lifetime while cold-switching 4 mA, and have a current handling capability of about 20 mA. In general, the contact resistance decreases over the first few thousand switch cycles, and degrades progressively when the switches are cycled beyond approximately 106 cycles. In this work, the microswitch contact resistance is studied on the basis of a clean metal contact resistance model. Comparison of the measured contact resistance (measured as a function of contact force) with the characteristics predicted by the model shows approximate agreement. The discrepancies between the model characteristics and measurements are discussed briefly.}, number={1}, journal={Sensors and Actuators, A: Physical}, author={Majumder, S. and McGruer, N.E. and Adams, G.G. and Zavracky, P.M. and Morrison, R.H. and Krim, J.}, year={2001}, pages={19–26} }
 @article{borovsky_mason_krim_2000, title={Scanning tunneling microscope measurements of the amplitude of vibration of a quartz crystal oscillator}, volume={88}, ISSN={["0021-8979"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0346437680&partnerID=MN8TOARS}, DOI={10.1063/1.1289235}, abstractNote={We report highly accurate measurements of the vibrational amplitude of a transverse shear mode quartz resonator, obtained by directly imaging the surface oscillatory motion with a scanning tunneling microscope. Amplitude measurements, performed over a range of resonator drive levels and quality factors, agree with theoretical predictions to within a factor of two.}, number={7}, journal={JOURNAL OF APPLIED PHYSICS}, author={Borovsky, B and Mason, BL and Krim, J}, year={2000}, month={Oct}, pages={4017–4021} }
 @article{krim_1999, title={Quartz microbalance studies of superconductivity-dependent sliding friction - Reply}, volume={83}, ISSN={["1079-7114"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-4244148930&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.83.1262}, abstractNote={A Reply to the Comment by R. L. Renner, J. E. Rutledge, and P. Taborek.Received 19 March 1999DOI:https://doi.org/10.1103/PhysRevLett.83.1262©1999 American Physical Society}, number={6}, journal={PHYSICAL REVIEW LETTERS}, publisher={American Physical Society (APS)}, author={Krim, J}, year={1999}, month={Aug}, pages={1262–1262} }
 @article{braiman_hentschel_family_mak_krim_1999, title={Tuning friction with noise and disorder}, volume={59}, ISSN={["1063-651X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001044961&partnerID=MN8TOARS}, DOI={10.1103/physreve.59.r4737}, abstractNote={We present numerical and experimental evidence which demonstrates that under certain conditions friction can be reduced by spatial disorder and/or thermal noise. We discuss possible mechanisms for this behavior.}, number={5}, journal={PHYSICAL REVIEW E}, author={Braiman, Y and Hentschel, HGE and Family, F and Mak, C and Krim, J}, year={1999}, month={May}, pages={R4737–R4740} }
 @article{dayo_krim_1998, title={Atomic-scale friction in Xe/Ag and N-2/Pb}, volume={19}, ISSN={["0195-928X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032058242&partnerID=MN8TOARS}, DOI={10.1023/A:1022638905940}, number={3}, journal={INTERNATIONAL JOURNAL OF THERMOPHYSICS}, author={Dayo, A and Krim, J}, year={1998}, month={May}, pages={827–834} }
 @inproceedings{majumder_mcgruer_zavracky_morrison_adams_krim_1998, title={Contact resistance modeling and measurements of an electrostatically actuated micromechanical switch}, volume={66}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032296788&partnerID=MN8TOARS}, booktitle={American Society of Mechanical Engineers, Dynamic Systems and Control Division (Publication) DSC}, author={Majumder, Sumit and McGruer, N.E. and Zavracky, Paul M. and Morrison, Richard H. and Adams, George G. and Krim, Jacqueline}, year={1998}, pages={341–346} }
 @article{robbins_krim_1998, title={Energy dissipation in interfacial friction}, volume={23}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032097541&partnerID=MN8TOARS}, DOI={10.1557/S088376940003058X}, abstractNote={In order to gain a fundamental understanding of friction, one must understand how the energy associated with work performed to overcome the frictional force is converted into heat at the molecular level. One of the simplest possible geometries in which friction can occur, and thus be studied, is that of a fluid or crystalline layer adsorbed on the surface of an ideal, atomically flat crystal. This system is ideal for studies of “interfacial” friction—that is, friction attributable to atoms and molecules immediately adjacent to the plane along which sliding occurs. Moreover it is directly accessible to experiments with a quartz crystal microbalance (QCM) and to theoretical studies through analytic calculations or molecular-dynamics (MD) simulations. The geometry is vastly simpler than that of contact between macroscopic objects in which the friction necessarily reflects the collective behavior of a multitude of buried contacts. (See the article by T. Baumberger and C. Caroli in this issue.) It is also far simpler than a case in which shear occurs within the bulk of a material rather than being confined to an interface. (See the article by D.A. Rigney and J.E. Hammerberg in this issue.) Nonetheless even in this simple geometry, friction can be far from negligible. A remarkable range of shear stresses, from 10−2 to 1010 N/m2, have been measured by a variety of techniques for wear-free geometries involving contact between crystalline interfaces.}, number={6}, journal={MRS Bulletin}, author={Robbins, M.O. and Krim, J.}, year={1998}, pages={23–26} }
 @article{krim_1998, title={Fundamentals of Friction}, volume={23}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-58149181860&partnerID=MN8TOARS}, DOI={10.1557/S0883769400030578}, abstractNote={By most recent estimates, improved attention to friction and wear would save developed countries up to 1.6% of their gross national product—over $100 billion annually in the United States alone. It is thus not surprising that tribomaterials, materials designed for use in moving contact (sliding, rolling, abrasive, etc.) have for decades attracted the interests of materials scientists and mechanical and chemical engineers. However the field of tribology is hardly a recent one. Such tribological advances as Leonardo da Vinci's design of intricate gears and bearings (some of which were not built until the Industrial Revolution provided sufficiently strong materials) and the landmark 18th century development of a timepiece allowing accurate longitudinal positioning of ships at sea (accomplished via a self-lubricating wooden gear) could easily be termed “modern,” given the overall longevity of the field.}, number={6}, journal={MRS Bulletin}, author={Krim, J.}, year={1998}, pages={20–22} }
 @article{mak_krim_1998, title={Quartz-crystal microbalance studies of the velocity dependence of interfacial friction}, volume={58}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001383615&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.58.5157}, abstractNote={We have employed a quartz-crystal microbalance technique to measure the vibrational amplitude dependence of quality factor shifts which occur when Kr monolayers adsorb on the microbalance’s gold electrodes. Assuming that the friction force is proportional to some power of the sliding velocity of the film relative to its substrate, such measurements allow one to infer whether or not the friction force law is linear in form. We have observed a linear friction law to be valid for a full monolayer of both liquid and solid krypton, for sliding speeds estimated to be in the range 3‐8 cm/s. The form of the friction law at lower coverages appears to be nonlinear, consistent with n,1 in a more general law, F}v n . @S0163-1829~98!01030-3#}, number={9}, journal={Physical Review B - Condensed Matter and Materials Physics}, author={Mak, C. and Krim, J.}, year={1998}, pages={5157–5159} }
 @inproceedings{majumder_mcgruer_adams_zavracky_zavracky_morrison_krim_1998, title={Study of contacts in an electrostatically actuated microswitch}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032309394&partnerID=MN8TOARS}, booktitle={Electrical Contacts, Proceedings of the Annual Holm Conference on Electrical Contacts}, author={Majumder, Sumit and McGruer, N.E. and Adams, George G. and Zavracky, A. and Zavracky, P.M. and Morrison, Richard H. and Krim, Jacqueline}, year={1998}, pages={127–132} }
 @article{dayo_alnasrallah_krim_1998, title={Superconductivity-dependent sliding friction}, volume={80}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0000218461&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.80.1690}, abstractNote={We have employed a quartz crystal microbalance technique to measure the friction associated with sliding of solid nitrogen along a lead surface, above and below the lead's superconducting transition temperature. The friction is observed to drop abruptly at the transition as the substrate enters the superconducting state. The observation signifies a new phenomenon, most likely attributable to electronic contributions to friction. While such contributions have been discussed and debated theoretically for a number of years, they have heretofore not been observed in any direct experimental fashion.}, number={8}, journal={Physical Review Letters}, author={Dayo, A. and Alnasrallah, W. and Krim, J.}, year={1998}, pages={1690–1693} }
 @article{tomassone_sokoloff_widom_krim_1997, title={Dominance of phonon friction for a xenon film on a silver (111) surface}, volume={79}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-6144266282&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.79.4798}, abstractNote={Molecular dynamic simulations for a Xe film sliding on an Ag(111) substrate are performed from the submonolayer through the bilayer regime, which, when compared to both friction and surface resistivity measurements, demonstrate that the friction in this system is dominated by phonon excitations. Slip times are found both by direct calculation of the decay of the center-of-mass velocity, as well as from the decay of the velocity correlation function. Agreement of the slip times from the two methods supports the occurrence of a friction force linear in velocity over a wide velocity range. {copyright} {ital 1997} {ital The American Physical Society}}, number={24}, journal={Physical Review Letters}, author={Tomassone, M.S. and Sokoloff, J.B. and Widom, A. and Krim, J.}, year={1997}, pages={4798–4801} }
 @article{krim_1997, title={Friction at the atomic scale}, volume={53}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0030733371&partnerID=MN8TOARS}, DOI={10.1038/scientificamerican1096-74}, number={1}, journal={Lubrication Engineering}, author={Krim, Jacqueline}, year={1997}, pages={8–13} }
 @inproceedings{majumder_mcgruer_zavracky_adams_morrison_krim_1997, title={Measurement and modeling of surface micromachined, electrostatically actuated microswitches}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0030675959&partnerID=MN8TOARS}, booktitle={International Conference on Solid-State Sensors and Actuators, Proceedings}, author={Majumder, Sumit and McGruer, N.E. and Zavracky, Paul M. and Adams, George G. and Morrison, Richard H. and Krim, Jacqueline}, year={1997}, pages={1145–1148} }
 @article{mak_krim_1997, title={Quartz crystal microbalance studies of disorder-induced lubrication}, volume={107}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0039771951&partnerID=MN8TOARS}, DOI={10.1039/a703481d}, abstractNote={We report here a quartz crystal microbalance (QCM) study of the friction associated with sliding of solid and liquid krypton films on ordered and disordered gold substrates, where lower friction is observed for the disordered substrates. The gold substrates on which the measurements were performed were prepared by depositing gold films onto polished quartz substrates held at 80 and 300 K, the 80 K samples being the more disordered of the two. The fact that lower friction levels were observed for more disordered systems may, potentially, be explained by the inhibition of phonon excitations in these systems.}, journal={Faraday Discussions}, publisher={Royal Society of Chemistry (RSC)}, author={Mak, Chihong and Krim, Jacqueline}, year={1997}, pages={389–397} }
 @inproceedings{kleban_krim_ruffing_1997, title={Skewed height distributions of kinetically roughened films}, volume={440}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0031378188&partnerID=MN8TOARS}, booktitle={Materials Research Society Symposium - Proceedings}, author={Kleban, P. and Krim, J. and Ruffing, C.}, year={1997}, pages={311–315} }
 @article{panella_chiarello_krim_1996, title={Adequacy of the lifshitz theory for certain thin adsorbed films}, volume={76}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0000571525&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.76.3606}, abstractNote={We have employed a quartz crystal microbalance technique to study the thickness versus pressuredependence of a variety of thin (0–5 nm) liquid films (water, cyclohexane, nitrogen, krypton, andxenon) adsorbed on metal surfaces. We observe the Lifshitz theory of van der Waals forces to providean excellent description of nitrogen adsorption, and an inadequate description of water adsorption, withthe remaining gases spanning the two extremes.}, number={19}, journal={Physical Review Letters}, author={Panella, V. and Chiarello, R. and Krim, J.}, year={1996}, pages={3606–3609} }
 @article{mecke_krim_1996, title={Adsorption isotherms and thermal fluctuations}, volume={53}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0000885117&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.53.2073}, abstractNote={The influence of thermal fluctuations on adsorption isotherms is calculated within the context of a selfconsistent mean-field theory, and it is found that such fluctuations cannot be neglected in the analysis of adsorption data. This result arises from our observation that substrate-induced hindrance of thermal fluctuations can significantly alter the form of an adsorption isotherm, particularly in the thin-film regime (’02 5n m ! which is most commonly probed by adsorption experiments. Previous experiments involving room-temperature adsorption on flat surfaces have been reanalyzed, and the reported discrepancies with the Lifshitz theory of van der Waals forces are found to be much reduced when thermal fluctuations of the thickness of the adsorbed layer are taken into account. Recently published data for nitrogen adsorption on rough substrates have also been reanalyzed, and the thermal fluctuations are found to be more important for thin adsorbed layers than undulations of the film induced by the roughness of the substrate. The analysis reveals that, as long suspected, the scaling regime of asymptotic divergence has not yet been reached for film thicknesses remaining below 5 nm.}, number={4}, journal={Physical Review B - Condensed Matter and Materials Physics}, author={Mecke, K. and Krim, J.}, year={1996}, pages={2073–2082} }
 @article{krim_1996, title={Atomic-scale origins of frictiont}, volume={12}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001626306&partnerID=MN8TOARS}, number={19}, journal={Langmuir}, author={Krim, J.}, year={1996}, pages={4564–4566} }
 @article{tomassone_krim_1996, title={Fractal scaling behavior of water flow patterns on inhomogeneous surfaces}, volume={54}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-2342449048&partnerID=MN8TOARS}, DOI={10.1103/PhysRevE.54.6511}, abstractNote={Stream patterns which form when water flows over an inhomogeneous surface are a commonly observed phenomenon in nature. Examples include the patterns which form on wet shower stalls, on windowpanes during rain storms, and on cool inclined surfaces when exposed to humidity. Such patterns consist of a hierarchy of streams which exhibit both splitting and joining, the net effect being a series of crossings which occur whenever two or more streams encounter each other as they make their way down the incline. The behavior is distinct from that of a river network @1–4# where, due to the effects of erosion, smaller tributaries flow into larger paths to form a treelike structure without crossings. In contrast, the stream patterns of interest here form from water droplets which impact or condense onto the surface of a noneroding, inhomogeneous surface inclined at some angle. They remain in place until they acquire a critical mass such that the gravitational forces which pull the droplets downward are able to overcome the various forces ~arising from surface tension effects, surface roughness, chemical inhomogeneities, etc.! which tend to pin the droplets in place. The droplets’ motion, once initiated, does not proceed in a direct downward fashion on account of the surface irregularities which are encountered. Instead it is slowed, redirected, or stopped entirely depending on the nature of the irregularities encountered. As the total water mass increases, it must, however, eventually reach a threshold beyond which connected streams flow with finite velocity from top to bottom. The transition is in many ways reminiscent of avalanches @5# and depinning transitions which occur in a variety of systems @6#. We report here a measurement of the scaling properties of such a pattern for water flowing close to threshold conditions, and compare this result to recent theoretical predictions for fluid flow over randomly rough surfaces @7,8#.}, number={6}, journal={Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics}, author={Tomassone, M.S. and Krim, J.}, year={1996}, pages={6511–6515} }
 @article{daly_krim_1996, title={Friction and damping of Xe/Ag(111)}, volume={368}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0030412959&partnerID=MN8TOARS}, DOI={10.1016/S0039-6028(96)01027-8}, abstractNote={We have measured the force required to slide molecularly thin xenon films along Ag(111), and observe that the friction associated with the sliding is highly sensitive to the xenon film's lattice spacing. Our result sheds light on the relative contributions of lattice vibrations (phonons) and electronic mechanisms to the total frictional energy dissipation.}, number={1-3}, journal={Surface Science}, author={Daly, C. and Krim, J.}, year={1996}, pages={49–54} }
 @article{daly_krim_1996, title={Sliding friction of solid xenon monolayers and bilayers on Ag(111)}, volume={76}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0000162657&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.76.803}, abstractNote={We have measured the force required to slide one- and two-atom-thick solid films of xenon along a Ag(111) surface, and observe that the friction associated with the bilayer is approximately 25% greater than that associated with the monolayer. Our result sheds new light on the nature of atomic-scale frictional energy dissipation mechanisms, and demonstrates how localized to an interface such mechanisms can be.}, number={5}, journal={Physical Review Letters}, author={Daly, C. and Krim, J.}, year={1996}, pages={803–806} }
 @article{heyvaert_krim_van haesendonck_bruynseraede_1996, title={Surface morphology and kinetic roughening of Ag on Ag(111) studied with scanning tunneling microscopy}, volume={54}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0030193584&partnerID=MN8TOARS}, DOI={10.1103/PhysRevE.54.349}, abstractNote={The topography of Ag grown on Ag~111! measured with scanning tunneling microscopy reveals threedimensional, layered islands for film thicknesses below 500 A. For thicker Ag films, the layered structures can no longer be observed. The induced surface roughness increases with increasing film thickness and corresponds to the formation of self-similar surfaces with roughness exponents H close to 1 for thicknesses up to 5000 A. Our results are compared to the relevant theoretical models. @S1063-651X~96!11307-6#}, number={1}, journal={Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics}, author={Heyvaert, I. and Krim, J. and Van Haesendonck, C. and Bruynseraede, Y.}, year={1996}, pages={349–353} }
 @article{krim_daly_dayo_1995, title={Electronic contributions to sliding friction}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-11744362870&partnerID=MN8TOARS}, DOI={10.1007/BF00209775}, number={2-3}, journal={Tribology Letters}, author={Krim, J. and Daly, C. and Dayo, A.}, year={1995}, pages={211–218} }
 @inproceedings{krim_panella_1995, title={Probing surface roughness and porosity through adsorption of wetting layers}, volume={366}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029229028&partnerID=MN8TOARS}, booktitle={Materials Research Society Symposium - Proceedings}, author={Krim, J. and Panella, V.}, year={1995}, pages={231–239} }
 @book{panella_krim_1994, title={Adsorbate surface tension effects for isotherms recorded on fractally rough surfaces}, volume={87}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77956926032&partnerID=MN8TOARS}, DOI={10.1016/S0167-2991(08)63068-2}, abstractNote={We report an adsorption isotherm study of two liquids (nitrogen and oxygen) adsorbed on fractally rough silver surfaces. We observe strikingly different adsorption behavior, and attribute this to a difference in the surface tension between the two adsorbates. Our results provide insight to the problem of whether surface tension effects must be included in the analysis of adsorption isotherm data for rough substrates.}, number={C}, journal={Studies in Surface Science and Catalysis}, author={Panella, V. and Krim, J.}, year={1994}, pages={91–98} }
 @article{panella_krim_1994, title={Adsorption isotherm study of the fractal scaling behavior of vapor-deposited silver films}, volume={49}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001578312&partnerID=MN8TOARS}, DOI={10.1103/PhysRevE.49.4179}, abstractNote={Adsorption isotherm measurements have been carried out with a quartz microbalance on vapor-deposited silver films, to investigate whether fractal scaling is present. Fractal scaling is in evidence for films deposited at slightly off-normal incidence angles onto substrates held at 77 K. A range of thicknesses has been studied to assess the overall capabilities of adsorption as a probe of dynamic, as well as static, scaling behavior.}, number={5}, journal={Physical Review E}, author={Panella, V. and Krim, J.}, year={1994}, pages={4179–4184} }
 @article{mak_daly_krim_1994, title={Atomic-scale friction measurements on silver and chemisorbed oxygen surfaces}, volume={253}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0028744590&partnerID=MN8TOARS}, DOI={10.1016/0040-6090(94)90318-2}, abstractNote={A quartz microbalance technique was employed to measure characteristic slip times for ethane and ethylene monolayers adsorbed on silver and chemisorbed oxygen/silver surfaces. These systems have been suggested as model systems for studies of the relative contributions of electronic and phonon processes towards frictional energy losses. Slip times for the chemisorbed oxygen/silver surfaces are observed to be longer than those for silver. Based on this observation, it is argued that electronic contributions to friction should be considered whenever conducting surfaces are involved. Potential connections between the atomic-scale result and macroscopic observation are discussed.}, number={1-2}, journal={Thin Solid Films}, author={Mak, C. and Daly, C. and Krim, J.}, year={1994}, pages={190–193} }
 @article{chiarello_krim_thompson_1994, title={Quartz crystal microbalance and synchrotron X-ray reflectivity study of water and liquid xenon adsorbed on gold and quartz}, volume={306}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0028414043&partnerID=MN8TOARS}, DOI={10.1016/0039-6028(94)90077-9}, abstractNote={The adsorption of water on gold, liquid xenon on gold, and liquid xenon on quartz was studied by use of a combined quartz crystal microbalance and synchrotron X-ray reflectivity technique. This technique can simultaneously provide the quantity of adsorbed mass, the adsorbed layer thickness, and the real-space electron density profile of the adsorbed layer/vapor interface. These systems were chosen to cover a range of wetting scenarios, based on simple theoretical predictions for their wetting behavior.}, number={3}, journal={Surface Science}, author={Chiarello, R.P. and Krim, J. and Thompson, C.}, year={1994}, pages={359–366} }
 @inproceedings{palasantzas_krim_1994, title={Scanning tunneling microscopy study of the dynamic scaling properties of rough vapor-deposited silver films}, volume={317}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0027940959&partnerID=MN8TOARS}, booktitle={Materials Research Society Symposium Proceedings}, author={Palasantzas, G. and Krim, J.}, year={1994}, pages={111–116} }
 @article{palasantzas_krim_1994, title={Scanning tunneling microscopy study of the thick film limit of kinetic roughening}, volume={73}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-3743120964&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.73.3564}, abstractNote={The spatial and temporal scaling behaviors of vapor-deposited silver films have been investigated by means of scanning tunneling microscopy for the film thickness range ≈10–1000 nm. The roughness, growth, and dynamic scaling exponents have been independently measured (α = 0.82 ± 0.05, β = 0.29 ± 0.06, and z = 2.5 ± 0.5), and they exhibit no evolution with film thickness.}, number={26}, journal={Physical Review Letters}, author={Palasantzas, G. and Krim, J.}, year={1994}, pages={3564–3567} }
 @article{widom_krim_1994, title={Spreading diffusion and its relation to sliding friction in molecularly thin adsorbed films}, volume={49}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0342805404&partnerID=MN8TOARS}, DOI={10.1103/PhysRevE.49.4154}, abstractNote={The Einstein relations between frictional transport and diffusion coefficients are applied to the special case of a molecularly thin adsorbed film in order to demonstrate the equivalence between film-substrate sliding friction and the collective spreading diffusion properties of the film on its substrate.}, number={5}, journal={Physical Review E}, author={Widom, A. and Krim, J.}, year={1994}, pages={4154–4156} }
 @article{thompson_palasantzas_feng_sinha_krim_1994, title={X-ray-reflectivity study of the growth kinetics of vapor-deposited silver films}, volume={49}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001590052&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.49.4902}, abstractNote={X-ray-reflectivity measurements have been carried out on silver films which were vapor deposited onto silicon substrates, to investigate the thickness evolution of the film’s surface roughness. The growth exponent was found to be β=0.26±0.05, and the roughness exponenet was found to be H=0.70±0.10.}, number={7}, journal={Physical Review B}, author={Thompson, C. and Palasantzas, G. and Feng, Y.P. and Sinha, S.K. and Krim, J.}, year={1994}, pages={4902–4907} }
 @article{sokoloff_krim_widom_1993, title={Determination of an atomic-scale frictional force law through quartz-crystal microbalance measurements}, volume={48}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001582248&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.48.9134}, abstractNote={A method is proposed for interpreting the results of recent quartz microbalance measurements of shear friction, based on a model in which the friction is assumed to be proportional to a power of the velocity of the adsorbed film relative to the microbalance. The amplitude dependence of the quality factor Q of this model for the microbalance is shown to depend critically on the exponent of the velocity in the force law, allowing one to infer this exponent from experiment.}, number={12}, journal={Physical Review B}, author={Sokoloff, J.B. and Krim, J. and Widom, A.}, year={1993}, pages={9134–9137} }
 @article{palasantzas_krim_1993, title={Effect of the form of the height-height correlation function on diffuse x-ray scattering from a self-affine surface}, volume={48}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001158085&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.48.2873}, abstractNote={Height-height correlations for self-affine surfaces with finite horizontal cutoffs are generally modeled by exponential forms. Three mathematically acceptable, alternate forms for the height-height correlation function are investigated, to explore their impact on the analysis of diffuse x-ray-reflectivity data. The appropriateness of these functions to actual physical samples is explored through comparison with x-ray-reflectivity and scanning-tunneling-microscopy data recorded on known self-affine surfaces.}, number={5}, journal={Physical Review B}, author={Palasantzas, G. and Krim, J.}, year={1993}, pages={2873–2877} }
 @article{krim_indekeu_1993, title={Roughness exponents: A paradox resolved}, volume={48}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0000009937&partnerID=MN8TOARS}, DOI={10.1103/PhysRevE.48.1576}, abstractNote={The spatial scaling behavior of a self-affine surface is parametrized with what is commonly referred to as a «roughness» exponent. The paradox of whether large or small values of this exponent correspond to «rougher» surfaces is resolved here}, number={2}, journal={Physical Review E}, author={Krim, J. and Indekeu, J.O.}, year={1993}, pages={1576–1578} }
 @article{krim_heyvaert_van haesendonck_bruynseraede_1993, title={Scanning tunneling microscopy observation of self-affine fractal roughness in ion-bombarded film surfaces}, volume={70}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-3242877310&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.70.57}, abstractNote={We describe a straightforward method for obtaining a precise value for the fractal dimension (self-affine scaling exponent) of a surface, via scanning tunneling microscopy. It is applied to investigate ion-beam erosion of an iron film surface, provoding strong support for the applicability of scaling theory to submicron erosion processes. A self-affine surface with scaling exponent H=0.53\ifmmode\pm\else\textpm\fi{}0.02 is observed to develop.}, number={1}, journal={Physical Review Letters}, author={Krim, J. and Heyvaert, I. and Van Haesendonck, C. and Bruynseraede, Y.}, year={1993}, pages={57–60} }
 @book{krim_panella_1991, title={Characterization of The Surface Fractal Dimension of Evaporated Silver and Gold Films Through Adsorption Isotherm Measurements}, volume={62}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77956905664&partnerID=MN8TOARS}, DOI={10.1016/S0167-2991(08)61326-9}, abstractNote={Thin solid films are receiving much current attention as model systems for nonequilibrium growth processes and also on account of their potential for use as protective overcoats. The technique of adsorption is particularly advantageous for the characterization of the roughness and porosity of such films because of the microscopic size of the probe and because the surface area probed by the adsorbed monolayer includes that contained in pores. Adsorption studies have been carried out for various silver and gold films which have been deposited under controlled conditions onto the surface electrodes of a quartz crystal microbalance. We have studied films deposited at rates between .5 and 75 Å/sec and at temperatures ranging from 80–500 K. Within this range, there results a wide variety of film behavior, ranging from amorphous to crystalline to porous to potentially self-affine fractal structures.}, number={C}, journal={Studies in Surface Science and Catalysis}, author={Krim, J. and Panella, V.}, year={1991}, pages={217–224} }
 @article{krim_solina_chiarello_1991, title={Nanotribology of a Kr monolayer: A quartz-crystal microbalance study of atomic-scale friction}, volume={66}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0002696032&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.66.181}, abstractNote={A quartz-crystal microbalance has been utilized to probe sliding-friction effects in Kr monolayers undergoing solidification on Au and Ag surfaces. Solid layers are observed to be far more sensitive to surface morphology than liquids. The behavior of liquid layers is consistent with a frictional force whose magnitude is a nonlinear function of the sliding velocity.}, number={2}, journal={Physical Review Letters}, author={Krim, J. and Solina, D.H. and Chiarello, R.}, year={1991}, pages={181–184} }
 @article{krim_chiarello_1991, title={Sliding friction measurements of molecularly thin films}, volume={9}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0000339645&partnerID=MN8TOARS}, DOI={10.1116/1.577274}, abstractNote={Slippage behavior of Xe and Kr monolayers and bilayers adsorbed on gold substrates has been investigated by means of a quartz crystal microbalance. The experiments have been carried out for both solid and liquid layers, and also for films which solidify as the surrounding vapor pressure is increased. Measurements carried out on bilayer films indicate moderate increases in slippage for both liquid and solid films as the second layer condenses. Solid films are observed to exhibit greater slippage than liquids on smooth substrates.}, number={4}, journal={Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films}, author={Krim, J. and Chiarello, R.}, year={1991}, pages={2566–2569} }
 @article{chiarello_panella_krim_thompson_1991, title={X-ray reflectivity and adsorption isotherm study of fractal scaling in vapor-deposited films}, volume={67}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0000527586&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.67.3408}, abstractNote={We have carried out x-ray reflectivity and adsorption measurements on thermally evaporated silver and gold films deposited onto substrates held at 60, 300, and 500 K to investigate whether the surfaces of such films are fractal in nature. Both techniques indicate self-affine fractal scaling for Ag films deposited at near-normal incidence onto substrates held at 80 K.}, number={24}, journal={Physical Review Letters}, author={Chiarello, R. and Panella, V. and Krim, J. and Thompson, C.}, year={1991}, pages={3408–3411} }
 @article{watts_krim_widom_1990, title={Experimental observation of interfacial slippage at the boundary of molecularly thin films with gold substrates}, volume={41}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001558910&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.41.3466}, abstractNote={Physisorbed monolayers and multilayers adsorbed on the surface electrodes of a resonating quartz microbalance produce shifts in both the frequency and amplitude of the oscillator. The shift in frequency results from mass loading and the shift in amplitude results from film dissipation effects. We have measured these shifts for molecularly thin nitrogen and krypton films and observe levels of film dissipation which cannot be adequately accounted for within the context of the ``no-slip'' boundary condition of hydrodynamics. The data provide strong evidence that the excess dissipation arises from slippage at the film substrate interface since the film thicknesses studied are negligible compared to the viscous penetration depths of the respective materials.}, number={6}, journal={Physical Review B}, author={Watts, E.T. and Krim, J. and Widom, A.}, year={1990}, pages={3466–3472} }
 @article{pfeifer_cole_krim_1990, title={Pfeifer, Cole, and Krim reply}, volume={65}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-10844290526&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.65.663}, number={5}, journal={Physical Review Letters}, author={Pfeifer, P. and Cole, M.W. and Krim, J.}, year={1990}, pages={663} }
 @article{krim_watts_digel_1990, title={Slippage of simple liquid films adsorbed on silver and gold substrates}, volume={8}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001291899&partnerID=MN8TOARS}, DOI={10.1116/1.576524}, abstractNote={The amplitude of vibration of a quartz crystal oscillator decreases slightly when a film adsorbs on its surface. Measurement of this decrease in amplitude allows one to quantitatively deduce the solid–liquid interfacial viscosity and the degree to which the film ‘‘slips’’ due to the oscillatory motion. Experiments have been carried out on various ‘‘model interfaces,’’ including xenon and nitrogen on gold, and water and cyclohexane on silver. Monolayers and bilayers of these films are observed to exhibit greater average slippage than thick films of the corresponding bulk material. The more massive monolayers are observed to exhibit shorter slip times.}, number={4}, journal={Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films}, author={Krim, J. and Watts, E.T. and Digel, J.}, year={1990}, pages={3417–3420} }
 @article{chiarello_krim_1989, title={Influence of Surface Melting Characteristics on the Wetting Behavior of Solid Adsorbed Films}, volume={5}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33845183829&partnerID=MN8TOARS}, DOI={10.1021/la00087a005}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInfluence of surface melting characteristics on the wetting behavior of solid adsorbed filmsR. Chiarello and J. KrimCite this: Langmuir 1989, 5, 3, 567–570Publication Date (Print):May 1, 1989Publication History Published online1 May 2002Published inissue 1 May 1989https://pubs.acs.org/doi/10.1021/la00087a005https://doi.org/10.1021/la00087a005research-articleACS PublicationsRequest reuse permissionsArticle Views42Altmetric-Citations3LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts}, number={3}, journal={Langmuir}, author={Chiarello, R. and Krim, J.}, year={1989}, pages={567–570} }
 @article{reinisch_kaiser_krim_1989, title={Measurement of protein hydration shells using a quartz microbalance}, volume={63}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-25744458130&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.63.1743}, abstractNote={The protein myoglobin is dried on the surface electrodes of a 5 MHz quartz crystal oscillator. As the humidity above the film increases, the protein absorbs water and develops a hydration shell. The oscillator frequency shift measures the mass of absorbed water. Dramatic incremental decreases in the amplitude of vibration are also observed, corresponding to a softening of the protein structure and subsequent energy dissipation (damping) of the oscillations. The transition of a protein from a dry more rigid structure to a semifluid hydrated state is observed to occur in discrete steps. This first study is presented to demonstrate the viability of the technique, and the important information one can obtain with the quartz microbalance. The experiment can be repeated as a function of crystal frequency, using a number of crystals from 10 kHz to 100 MHz. The damping of the crystal should, of course, decrease when the frequency of the crystal differs from the frequencies of the protein fluctuations. In addition, the temperature can be varied. The temperature of protein will change the spectrum of protein fluctuations. New information concerning the temperature dependence of the protein internal viscosity could be obtained from this technique. The experiment can also be repeated using different proteins. We anticipate a number of interesting and informative studies to follow. This work has been submitted to Physical Review Letters (1989).}, number={16}, journal={Physical Review Letters}, author={Reinisch, L. and Kaiser, R.D. and Krim, J.}, year={1989}, pages={1743–1746} }
 @article{pfeifer_wu_cole_krim_1989, title={Multilayer adsorption on a fractally rough surface}, volume={62}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0000984718&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.62.1997}, abstractNote={Models are proposed for thick-film-coverage adsorption on a general fractal surface. The basic idea is that long-range dispersion forces dominate the thermodynamic behavior. The analysis predicts the coverage to be proportional to [ln(${P}_{0}$/P${)]}^{(D\mathrm{\ensuremath{-}}3)/3}$ where P/${P}_{0}$ is the relative vapor pressure and D is the fractal dimension of the surface. Experimental examples for this behavior are presented. They are rough Ag surfaces, giving D=2.30. .AE}, number={17}, journal={Physical Review Letters}, author={Pfeifer, P. and Wu, Y.J. and Cole, M.W. and Krim, J.}, year={1989}, pages={1997–2000} }
 @article{wang_krim_1989, title={Roughness and porosity characterization of carbon and magnetic films through adsorption isotherm measurements}, volume={7}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0000232147&partnerID=MN8TOARS}, DOI={10.1116/1.575881}, abstractNote={Hard carbon films are receiving much current attention on account of their potential use as protective overcoats. The tribological properties have an important influence on the functional performance of the films and can be probed through studies of film porosity and roughness. The technique of adsorption is particularly advantageous for this type of investigation because the area coated by an adsorbed monolayer is precisely that involved when the protective coating is exposed to the atmosphere. Adsorption studies have been carried out for both carbon and magnetic thin films which have been deposited onto the surface electrodes of quartz-crystal microbalances. These studies provide (i) an immediate determination of whether the film is rough or porous, and (ii) if porous, an indication of pore morphology.}, number={3}, journal={Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films}, author={Wang, C.L. and Krim, J.}, year={1989}, pages={2481–2485} }
 @article{krim_widom_1988, title={Damping of a crystal oscillator by an adsorbed monolayer and its relation to interfacial viscosity}, volume={38}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001721125&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.38.12184}, abstractNote={The acoustic impedance of a monolayer adsorbed on the surface of a resonating quartz microbalance produces a shift in both the frequency and vibrational amplitude of the oscillator. The relation between acoustic impedance and fluctuations in film momentum is rigorously derived via the fluctuation-dissipation theorem within the context of two-dimensional fluid mechanics. The calculations reveal that the film-substrate interfacial viscosity can be deduced from measurements of acoustic impedance.}, number={17}, journal={Physical Review B}, author={Krim, J. and Widom, A.}, year={1988}, pages={12184–12189} }
 @article{larese_harada_passell_krim_satija_1988, title={Neutron-scattering study of methane bilayer and trilayer films on graphite}, volume={37}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0000747055&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.37.4735}, abstractNote={The results of a neutron-diffraction study of the multilayer growth properties of methane on a graphite substrate are presented. The experiments, performed over an extended temperature range, follow the layering behavior from the submonolayer region to approximately three layers. The completed monolayer film is found to be overcompressed with respect to the bulk value. A stacking sequence and lattice parameter close to that of the bulk solid are found near three layers. The bilayer region, however, is characterized by a diffraction pattern which is not consistent with two layers in perfect registry with one another.}, number={9}, journal={Physical Review B}, author={Larese, J.Z. and Harada, M. and Passell, L. and Krim, J. and Satija, S.}, year={1988}, pages={4735–4742} }
 @article{chiarello_coulomb_krim_wang_1988, title={Surface melting of multilayer oxygen films on graphite studied by neutron diffraction}, volume={38}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0038942379&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.38.8967}, abstractNote={The results of a neutron-diffraction study of the melting properties of multilayer oxygen films are presented. The experiments have been carried out between 30 and 55 K on films ranging from 2 to 8 layers in thickness. A compound solid-liquid film is observed in the range 40--48 K. This composite film results from surface melting of the solid film phase which is present at 40 K. The thickness of its melted component is proportional to ln(${T}_{t}$-T), where ${T}_{t}$ is the melting temperature of bulk oxygen. The structure of its solid component is nearly identical to that of the bulk \ensuremath{\beta} phase. The data suggest that multiple wetting transitions may be present in this system.}, number={13}, journal={Physical Review B}, author={Chiarello, R. and Coulomb, J.P. and Krim, J. and Wang, C.L.}, year={1988}, pages={8967–8973} }
 @article{krim_bouzidi_1987, title={Summary abstract: Influence of film melting characteristics on the wetting behavior of multilayer oxygen films adsorbed on graphite}, volume={5}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84957274808&partnerID=MN8TOARS}, DOI={10.1116/1.574802}, abstractNote={Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation J. Krim, J. P. Coulomb, J. Bouzidi; Summary Abstract: Influence of film melting characteristics on the wetting behavior of multilayer oxygen films adsorbed on graphite. J. Vac. Sci. Technol. A 1 July 1987; 5 (4): 1096–1097. https://doi.org/10.1116/1.574802 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAVS: Science & Technology of Materials Interfaces and ProcessingJournal of Vacuum Science & Technology A Search Advanced Search |Citation Search}, number={4}, journal={Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films}, author={Krim, J. and Bouzidi, J.}, year={1987}, pages={1096–1097} }
 @article{krim_coulomb_bouzidi_1987, title={Triple-point wetting and surface melting of oxygen films adsorbed on graphite}, volume={58}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-4243566309&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.58.583}, abstractNote={Neutron diffraction experiments on multilayer oxygen films on graphite have been carried out between 30 and 55 K. A compound solid-liquid film is observed in the range 40--48 K, exhibiting properties consistent with surface melting. The quantity of liquid in this range varies as ln(${\mathrm{T}}_{\mathrm{t}}$-T). This behavior ceases when the thickness of the liquid component reaches that of the film itself, giving rise to the ``metastable liquid'' phase of the triple point wetting process.}, number={6}, journal={Physical Review Letters}, author={Krim, J. and Coulomb, J.P. and Bouzidi, J.}, year={1987}, pages={583–586} }
 @article{gay_dutheil_krim_suzanne_1986, title={A LEED study of methane films adsorbed on graphite in the monolayer range}, volume={177}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-4644309491&partnerID=MN8TOARS}, DOI={10.1016/0039-6028(86)90255-4}, abstractNote={The submonolayer structural properties of methane on graphite have been studied by means of low energy electron diffraction in the range 30–67 K, allowing the determination of the orientational epitaxy of the CH4 monolayer adsorbed on graphite single crystals. Thermodynamic adsorption properties have also been measured, and are compared with earlier volumetric measurements recorded in the temperature range 77–84 K.}, number={1}, journal={Surface Science}, author={Gay, J.M. and Dutheil, A. and Krim, J. and Suzanne, J.}, year={1986}, pages={25–35} }
 @article{krim_1986, title={Fiber texture and surface composition of evaporated gold films on quartz}, volume={137}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0022690758&partnerID=MN8TOARS}, DOI={10.1016/0040-6090(86)90031-3}, abstractNote={The fiber texture, surface composition and homogeneity of polycrystalline films of gold 300–2000 Å thick evaporated onto quartz in the pressure range from 1.5 × 10−2 to 2 × 10−7 Pa were investigated by means of X-ray diffraction, electron microscopy, Auger electron spectroscopy and gas sorption experiments. No qualitative differences are observed between the films characterized here and previous results reported for glass substrates: a (111) fiber orientation is observed and is enhanced as the substrate temperature, during or after the deposition, is increased. The percentage of gold present at the surface and the surface homogeneity are more sensitive to the cleaning and outgassing procedure than to the actual pressure during deposition. The uniformity of the quartz substrate has little influence on the surface homogeneity of the gold film.}, number={2}, journal={Thin Solid Films}, author={Krim, J.}, year={1986}, pages={297–303} }
 @article{krim_gay_suzanne_lerner_1986, title={INCOMPLETE WETTING OF METHANE ON GRAPHITE AT LOW TEMPERATURES.}, volume={47}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0022796741&partnerID=MN8TOARS}, DOI={10.1051/jphys:0198600470100175700}, abstractNote={Le mouillage du graphite par le methane a ete etudie par diffraction d'electrons lents et d'electrons rapides dans le domaine de temperature 14-40 K. Un mouillage incomplet (formation de cristallites) est apparu sur toute cette gamme de temperature pour des films d'epaisseur a 15 couches. Les chaleurs isosteriques d'adsorption des 2eme, 3eme, 4eme couches mesurees sont en accord avec celles determinees par ailleurs a 77 K}, number={10}, journal={Journal de physique Paris}, author={Krim, J. and Gay, J.M. and Suzanne, J. and Lerner, E.}, year={1986}, pages={1757–1762} }
 @article{widom_krim_1986, title={Q factors of quartz oscillator modes as a probe of submonolayer-film dynamics}, volume={34}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001572307&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.34.1403}, abstractNote={That frequency shifts by quartz crystals oscillating in the transverse shear mode can be used to determine adsorption isotherms for monolayer and submonolayer adsorbed films is well understood. Here, the nature of the dynamical information contained in the quality factors of such modes is theoretically discussed.}, number={2}, journal={Physical Review B}, author={Widom, A. and Krim, J.}, year={1986}, pages={1403–1404} }
 @article{krim_suzanne_shechter_wang_taub_1985, title={A LEED and neutron diffraction study of hexane adsorbed on graphite in the monolayer range: uniaxial commensurate-incommensurate transition}, volume={162}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001229059&partnerID=MN8TOARS}, DOI={10.1016/0039-6028(85)90933-1}, abstractNote={The structure of a n-hexane molecule (C6H14) adsorbed on graphite has been studied by LEED and neutron diffraction in the range 100 to 177 K. Below 151 K the monolayer has an ordered herringbone structure. The rectangular unit mesh is commensurate 4 × √3 in only one direction. Along the other direction, the lattice constant is 5.3 ± 0.05 Å. With increasing coverage, a continuous uniaxial incommensurate to commensurate transition to a 2 × 4√3 phase occurs. At 151 K the ordered structure is replaced by a fluid-like phase, as indicated by a diffuse ring in the LEED pattern. This melting transition appears to be first order. The isosteric heat at monolayer condensation is measured to be 16 kcal/mol via LEED graphite spot intensity isotherms from 160 to 177 K.}, number={1-3}, journal={Surface Science}, author={Krim, J. and Suzanne, J. and Shechter, H. and Wang, R. and Taub, H.}, year={1985}, pages={446–451} }
 @article{migone_krim_dash_suzanne_1985, title={Incomplete wetting of He4 films on Ag and Au(111) surfaces}, volume={31}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-24544481165&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.31.7643}, abstractNote={The wetting behavior of $^{4}\mathrm{He}$ adsorbed on planar Ag and Au(111) surfaces has been studied by means of a quartz, high-frequency microbalance. Incomplete wetting was observed over the entire experimental temperature (T) range from below 1.4 K to 1 mK below the critical point. The limiting film thickness ${d}_{0}$ at coexistence with bulk liquid increases from about 10 layers at the \ensuremath{\lambda} point to more than 50 layers at the highest temperature. Over a considerable interval the T dependence of ${d}_{0}$ is consistent with the power law ${d}_{0}$\ensuremath{\propto}(${T}_{w}$-T${)}^{\mathrm{\ensuremath{-}}1}$ proposed by Dietrich and Schick for critical wetting. Below the \ensuremath{\lambda} point the frequency isotherms develop pronounced dips at pressures well below saturated vapor pressures ${P}_{0}$. The dips are associated with superfluid onset, and the clear separation between the dips and the abrupt increases in frequency at ${P}_{0}$ show that superfluid onset and bulk fluid condensation are independent phenomena.}, number={12}, journal={Physical Review B}, author={Migone, A.D. and Krim, J. and Dash, J.G. and Suzanne, J.}, year={1985}, pages={7643–7650} }
 @article{krim_dash_1985, title={Incomplete wetting of helium films}, volume={162}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0012410638&partnerID=MN8TOARS}, DOI={10.1016/0039-6028(85)90929-X}, abstractNote={Incomplete wetting of adsorbed He films is treated by a classical liquid slab model near T = 0. Several contributions to the chemical potential at coexistence are examined: cohesion, adhesion, compression and solidification by the substrate field, and interfacial energies.}, number={1-3}, journal={Surface Science}, author={Krim, J. and Dash, J.G.}, year={1985}, pages={421–425} }
 @article{bruch_gay_krim_1985, title={ON THE LIMIT OF COMPRESSION OF A PHYSISORBED MONOLAYER.}, volume={46}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0022038069&partnerID=MN8TOARS}, DOI={10.1051/jphys:01985004603042500}, abstractNote={Effects on the limit of monolayer compression of large changes in the first layer adatom-substrate holding potential e0 and of uniaxial registry of the monolayer are discussed. It is shown that if the monolayer-to-bilayer transition occurs with only small changes in the nearest neighbour spacing, the chemical potential there depends on the second-layer binding, but little on e0. Consequences of the particularly large variations in e0 for helium between substrates are discussed. Model calculations of the limit of compression for uniaxially registered Xe/Cu(110) are reported; the chemical potential at the transition is quite close to that for condensation of bulk Xe. The value of e0 for Xe/Cu(110) and the experimental determination of the monolayer latent heat of adsorption are discussed and a revised value is proposed for the latent heat.}, number={3}, journal={Journal de physique Paris}, author={Bruch, L.W. and Gay, J.M. and Krim, J.}, year={1985}, pages={425–433} }
 @article{bienfait_seguin_suzanne_lerner_krim_dash_1984, title={Complete and incomplete wetting of krypton and oxygen on graphite: Reentrant type-2 growth on a scale of substrate strength}, volume={29}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001051590&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.29.983}, abstractNote={Reflection high-energy electron-diffraction (RHEED) studies of krypton and oxygen films on basal-plane graphite show that the low-temperature mode of growth of Kr is type 1 (complete wetting) whereas that of ${\mathrm{O}}_{2}$ is type 2 (incomplete wetting). The present results extend earlier RHEED measurements on other gases, and indicate the existence of two distinct regimes of incomplete wetting growth separated by a narrow region of complete-wetting growth. These results, together with published work on other films, are analyzed on an improved scale of relative interaction parameters. Arguments are presented to suggest that the mechanisms for incomplete wetting are different in the weak and strong substrate regimes. The present study also shows certain distinct structural relationships between crystallites and layered film in the incomplete wetting growth regime.}, number={2}, journal={Physical Review B}, author={Bienfait, M. and Seguin, J.L. and Suzanne, J. and Lerner, E. and Krim, J. and Dash, J.G.}, year={1984}, pages={983–987} }
 @article{krim_dash_suzanne_1984, title={Triple-point wetting of light molecular gases on Au(111) surfaces}, volume={52}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-3342994465&partnerID=MN8TOARS}, DOI={10.1103/PhysRevLett.52.640}, abstractNote={Determination a l'aide d'une microbalance haute frequence des caracteristiques de mouillage d'Ar, Kr, Xe, N 2 , O 2 , methane et ethane adsorbes sur Au(111). Tous les gaz forment des films de mouillage incomplets au-dessous de leurs points triples et de mouillage complet au-dessus}, number={8}, journal={Physical Review Letters}, author={Krim, J. and Dash, J.G. and Suzanne, J.}, year={1984}, pages={640–643} }
 @article{muirhead_dash_krim_1984, title={Wetting and nonwetting of molecular films at zero temperature}, volume={29}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-24544479341&partnerID=MN8TOARS}, DOI={10.1103/PhysRevB.29.5074}, abstractNote={The wetting characteristics of classical rare gases adsorbed on smooth solid substrates at zero temperature are studied as a function of the molecule-substrate interaction. Comparisons of the relative stabilities of monolayers, bilayers, and trilayers with respect to each other and to the bulk solid phase show a succession of growth regimes with increasing substrate interaction strength relative to molecular pair interactions: nonwetting, incomplete wetting with maximum thicknesses of one layer, incomplete wetting with a mutually commensurate bilayer, and complete wetting. Their order of appearance and the values of substrate strength at crossover boundaries depend sensitively on substrate potential shape, substrate screening of interactions between adsorbate atoms, and the magnitude of the bulk solid energy. Close correspondence with experiment is obtained from Cole-Klein potentials with enhanced first-layer well depths and with substrate screening. This model has a narrow complete wetting region with boundaries at relative substrate strengths near those observed in films on graphite. The complete wetting regime is bounded on the high-strength side by incomplete wetting films consisting of mutually commensurate close-packed bilayers, and on the low-strength side by close-packed monolayers. At still weaker substrate potentials the adsorption is nonwetting. The layer densities of the incompletely wet films are found to be several percent greater than surface planes of the bulk solid, supporting the conjecture that the transition from complete to incomplete, with increasing substrate strength, is driven by structural mismatch between the film and the bulk solid. These features are consistent with observations of light molecular gases on graphite and other surfaces.}, number={9}, journal={Physical Review B}, author={Muirhead, R.J. and Dash, J.G. and Krim, J.}, year={1984}, pages={5074–5080} }
 @unpublished{fundamental mechanisms underlying the effectiveness of nanoparticle additives to lubricants: 25 examples linking nano- to macroscale friction, DOI={10.20944/preprints202405.0768.v1}, abstractNote={Studies of the fundamental origins of friction have undergone a rapid acceleration in recent years by providing valuable information on the nanoscale mechanisms responsible for the friction at the macroscopic level. Significant efforts have been directed into developing composite nanofluids and nanoparticle additives to unlock new tribological properties unattainable by traditional lub-ricants. The studies are now further evolving by developing methods to achieve active control of the nano- and/or mesoscale friction by application of magnetic and electric fields external to the contact. These methods constitute an area of rapidly growing interest, and they also are illumi-nating how the performance of conventional lubricants could be enhanced through synergistic addition of nanoparticles (NPs). This mini-review highlights 25 publications that collectively re-veal significant progress, as well as important outstanding challenges, to a fundamental under-standing of how the addition of NPs impacts the lubricant performance. The first two sections focus on the use of Quartz Crystal Microbalance (QCM), a technique that spans atomic to mac-roscale length and time scales. Subsequent sections expand to complimentary methods comparing results at the macro and atomic scale for similar materials. These studies highlight the pivotal role of the nanoparticle charge and surface treatment, while also indicating that rolling of nano-particles is ineffective and/or detrimental.} }