@article{wang_zou_araki_luening_kilcoyne_sokolov_ade_rafailovich_2010, title={Probing the Chain and Crystal Lattice Orientation in Polyethylene Thin Films by Near Edge X-ray Absorption Fine Structure (NEXAFS) Spectroscopy}, volume={43}, ISSN={["1520-5835"]}, DOI={10.1021/ma101213h}, abstractNote={The chain and the crystal unit cell orientation of linear low density polyethylene (LLDPE) were measured with near edge X-ray absorption fine structure (NEXAFS) spectroscopy. A strongly attractive substrate, silicon, and a weakly attractive substrate, mica, were used. For a 100 nm thick LLDPE film on the silicon substrate, the crystals exhibit an edge-on lamellar morphology, with the chains predominantly parallel to the substrate, and the orthorhombic unit cell ⟨a, b, c⟩ in the following approximate orientation: b and c are in the film plane with b along the crystal fibril direction and c perpendicular to the fibril direction and a perpendicular to the film plane. On the mica substrates, LLDPE films with thickness below 180 nm completely dewet the surface and form isolated droplets, while a film 366 nm thick crystallizes as spherulites with most of the chains perpendicular to the substrate before annealing and with a twisted lamellar structure after isothermal crystallization at 60 °C. The results demonst...}, number={19}, journal={MACROMOLECULES}, author={Wang, Yantian and Zou, Ying and Araki, Tohru and Luening, Jan and Kilcoyne, A. L. D. and Sokolov, Jonathan and Ade, Harald and Rafailovich, Miriam}, year={2010}, month={Oct}, pages={8153–8161} }
 @article{fujii_dupin_araki_armes_ade_2009, title={First Direct Imaging of Electrolyte-Induced Deswelling Behavior of pH-Responsive Microgels in Aqueous Media Using Scanning Transmission X-ray Microscopy}, volume={25}, ISSN={["0743-7463"]}, DOI={10.1021/la804212y}, abstractNote={Lightly cross-linked sterically stabilized poly(2-vinylpyridine) latexes exhibit pH-responsive behavior, undergoing a latex-to-microgel transition below pH 4.1 as a result of protonation of the pyridine pendent groups. We have examined both the latex and microgel states of such particles directly in aqueous solution using scanning transmission X-ray microscopy (STXM). Moreover, near-edge X-ray absorption fine structure (NEXAFS) spectroscopy studies confirm that the nitrogen atoms of the microgel particles are fully protonated at low pH. The addition of salt causes partial deswelling of these microgel particles, but spectroscopic analysis confirms the retention of their cationic character. This is the first direct visualization of the effect of electrolyte screening on microgel dimensions in aqueous solution. In each case, the observed particle dimensions are consistent with dynamic light scattering characterization, especially when polydispersity effects are taken into consideration.}, number={5}, journal={LANGMUIR}, author={Fujii, Syuji and Dupin, Damien and Araki, Tohru and Armes, Steven P. and Ade, Harald}, year={2009}, month={Mar}, pages={2588–2592} }
 @article{swaraj_wang_araki_mitchell_liu_gaynor_deshmukh_yan_mcneill_ade_2009, title={The utility of resonant soft x-ray scattering and reflectivity for the nanoscale characterization of polymers}, volume={167}, ISSN={["1951-6355"]}, DOI={10.1140/epjst/e2009-00946-3}, journal={EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS}, author={Swaraj, S. and Wang, C. and Araki, T. and Mitchell, G. and Liu, L. and Gaynor, S. and Deshmukh, B. and Yan, H. and McNeill, C. R. and Ade, H.}, year={2009}, month={Feb}, pages={121–126} }
 @article{cody_alexander_yabuta_kilcoyne_araki_ade_dera_fogel_militzer_mysen_2008, title={Organic thermometry for chondritic parent bodies}, volume={272}, ISSN={["0012-821X"]}, DOI={10.1016/j.epsl.2008.05.008}, abstractNote={Abstract A unique spectroscopic feature has been identified in a study of twenty-five different samples of meteoritic insoluble organic matter (IOM) spanning multiple chemical classes, groups, and petrologic types, using carbon X-ray Absorption Near Edge Structure (XANES) spectroscopy. The intensity of this feature, a 1s − σ⁎ exciton, appears to provide a precise measure of parent body metamorphism. The intensity of this exciton is also shown to correlate well with a large negative paramagnetic shift observed through solid state 13C NMR. Experiments reveal that upon heating primitive IOM is transformed into material that is indistinguishable from that in thermally processed chondrites, including the development of the 1s − σ⁎ exciton. A thermo-kinetic expression is derived from the experimental data that allows the intensity of the 1s − σ⁎ exciton to be used to estimated the effective temperature integrated over time. A good correlation is observed between the intensity of the 1s − σ⁎ exciton and previously published microRaman spectral data. These data provide a self-consistent organic derived temperature scale for the purpose of calibrating Raman based thermometric expressions.}, number={1-2}, journal={EARTH AND PLANETARY SCIENCE LETTERS}, author={Cody, G. D. and Alexander, C. M. O'D. and Yabuta, H. and Kilcoyne, A. L. D. and Araki, T. and Ade, H. and Dera, R. and Fogel, M. and Militzer, B. and Mysen, B. O.}, year={2008}, month={Jul}, pages={446–455} }
 @article{cody_ade_alexander_araki_butterworth_fleckenstein_flynn_gilles_jacobsen_kilcoyne_et al._2008, title={Quantitative organic and light-element analysis of comet 81P/Wild 2 particles using C-, N-, and O-mu-XANES}, volume={43}, ISSN={["1945-5100"]}, DOI={10.1111/j.1945-5100.2008.tb00627.x}, abstractNote={Abstract— Synchrotron‐based soft X‐ray micro‐analysis was performed on particles extracted from the Stardust aerogel collector in order to obtain detailed organic functional group information on any organic solids captured as part of the Principal Examination suite of analyses for samples from comet 81P/Wild 2. It is observed that cometary organic carbon captured in aerogel is present in a number of different manifestations and often intimately associated with silicates. Carbon X‐ray absorption near edge structure (XANES) spectra reveal considerable chemical complexity in all of the organic particles studied so far. Universally, the comet 81P/Wild 2 organic particles contain low concentrations of aromatic and/or olefinic carbon relative to aliphatic and heteroatom‐containing functional groups, e.g., amide, carboxyl, and alcohol/ethers. N‐XANES confirms the presence and assignments of these functional groups. In general, the XANES data record considerable chemical complexity across the range of organic samples currently analyzed. The atomic ratios, N/C and O/C, derived from XANES data reveal a wide range in heteroatom content; in all cases these elemental ratios are higher than that of primitive meteoritic organic matter. The wide range in chemistry, both in elemental abundances and specific organic functional groups, suggests that the comet 81P/Wild 2 organic solids may have multiple origins.}, number={1-2}, journal={METEORITICS & PLANETARY SCIENCE}, author={Cody, George D. and Ade, Harald and Alexander, Conel M. O'D. and Araki, Tohru and Butterworth, Anna and Fleckenstein, Holger and Flynn, George and Gilles, Mary K. and Jacobsen, Chris and Kilcoyne, A. L. D. and et al.}, year={2008}, pages={353–365} }
 @article{wang_araki_watts_harton_koga_basu_ade_2007, title={Resonant soft x-ray reflectivity of organic thin films}, volume={25}, ISSN={["0734-2101"]}, DOI={10.1116/1.2731352}, abstractNote={At photon energies close to absorption edges in the soft x-ray range, the complex index of refraction, n=1−δ−iβ, of organic materials varies rapidly as a function of photon energy in a manner that strongly depends on the chemical moieties and functionalities present in the material. The authors present details of how these molecular structure specific variations in the complex index of refraction can be utilized to enhance and tune the contrast in reflectivity experiments of organic films. This near edge contrast enhancement mimics the specific contrast achieved through deuterium labeling in neutron reflectivity (NR). This relatively new x-ray approach, resonant soft x-ray reflectivity (RSoXR), thus combines aspects of NR and conventional x-ray reflectivity (XR), yet does not require special chemical procedures. The capabilities of RSoXR are exemplified using a number of polymeric bi- and multilayers. Furthermore, a direct comparison of RSoXR to conventional x-ray reflectivity and NR for polystyrene and poly(methyl methacrylate) bilayers verifies that RSoXR is an excellent alternative tool for the characterization of organic thin films. The influence of the longitudinal and transverse coherence properties as well as the divergence of the x-ray or neutron beam on the capabilities and limitations of each reflectivity variant is discussed.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Wang, Cheng and Araki, Tohru and Watts, Benjamin and Harton, Shane and Koga, Tadanori and Basu, Saibal and Ade, Harald}, year={2007}, pages={575–586} }
 @article{brownlee_tsou_aleon_alexander_araki_bajt_baratta_bastien_bland_bleuet_et al._2006, title={Comet 81P/Wild 2 under a microscope}, volume={314}, ISSN={["1095-9203"]}, DOI={10.1126/science.1135840}, abstractNote={The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.}, number={5806}, journal={SCIENCE}, author={Brownlee, Don and Tsou, Peter and Aleon, Jerome and Alexander, Conel M. O'D. and Araki, Tohru and Bajt, Sasa and Baratta, Giuseppe A. and Bastien, Ron and Bland, Phil and Bleuet, Pierre and et al.}, year={2006}, month={Dec}, pages={1711–1716} }
 @article{si_araki_ade_kilcoyne_fisher_sokolov_rafailovich_2006, title={Compatibilizing bulk polymer blends by using organoclays}, volume={39}, ISSN={["1520-5835"]}, DOI={10.1021/ma060125+}, abstractNote={We have studied the morphology of blends of PS/PMMA, PC/SAN24, and PMMA/EVA and compared the morphologies with and without modified organoclay Cloisite 20A or Cloisite 6A clays. In each case we found a large reduction in domains size and the localization of the clay platelets along the interfaces of the components. The increased miscibility was accompanied in some cases, with the reduction of the system from multiple values of the glass transition temperatures to one. In addition, the modulus of all the systems increased significantly. A model was proposed where it was proposed that in-situ grafts were forming on the clay surfaces during blending and the grafts then had to be localized at the interfaces. This blending mechanism reflects the composition of the blend and is fairly nonspecific. As a result, this may be a promising technology for use in processing recycled blends where the composition is often uncertain and price is of general concern.}, number={14}, journal={MACROMOLECULES}, author={Si, Mayu and Araki, Tohru and Ade, Harald and Kilcoyne, A. L. D. and Fisher, Robert and Sokolov, Jonathan C. and Rafailovich, Miriam H.}, year={2006}, month={Jul}, pages={4793–4801} }
 @article{sandford_aleon_alexander_araki_bajt_baratta_borg_bradley_brownlee_brucato_et al._2006, title={Organics captured from comet 81P/Wild 2 by the Stardust spacecraft}, volume={314}, ISSN={["1095-9203"]}, DOI={10.1126/science.1135841}, abstractNote={Organics found in comet 81P/Wild 2 samples show a heterogeneous and unequilibrated distribution in abundance and composition. Some organics are similar, but not identical, to those in interplanetary dust particles and carbonaceous meteorites. A class of aromatic-poor organic material is also present. The organics are rich in oxygen and nitrogen compared with meteoritic organics. Aromatic compounds are present, but the samples tend to be relatively poorer in aromatics than are meteorites and interplanetary dust particles. The presence of deuterium and nitrogen-15 excesses suggest that some organics have an interstellar/protostellar heritage. Although the variable extent of modification of these materials by impact capture is not yet fully constrained, a diverse suite of organic compounds is present and identifiable within the returned samples.}, number={5806}, journal={SCIENCE}, author={Sandford, Scott A. and Aleon, Jerome and Alexander, Conel M. O'D. and Araki, Tohru and Bajt, Sasa and Baratta, Giuseppe A. and Borg, Janet and Bradley, John P. and Brownlee, Donald E. and Brucato, John R. and et al.}, year={2006}, month={Dec}, pages={1720–1724} }
 @article{araki_ade_stubbs_sundberg_mitchell_kortright_kilcoyne_2006, title={Resonant soft x-ray scattering from structured polymer nanoparticles}, volume={89}, DOI={10.1063/1.2356306}, abstractNote={The application of resonant soft x-ray scattering to chemically heterogeneous soft condensed matter materials is presented. Two structured styrene-acrylic polymer composite latex particles ∼230nm in diameter were utilized to delineate the potential utility of this technique. Angular scans at photon energies corresponding to strong scattering contrast between specific chemical moieties made it possible to infer the effective radii that correspond to the two polymer phases in the nanoparticles. The results show that resonant soft x-ray scattering should be a powerful complementary tool to neutron and hard x-ray scattering for the characterization of structured soft condensed matter nanomaterials.}, number={12}, journal={Applied Physics Letters}, author={Araki, T. and Ade, Harald and Stubbs, J. M. and Sundberg, D. C. and Mitchell, G. E. and Kortright, J. B. and Kilcoyne, A. L. D.}, year={2006} }
 @article{zou_araki_appel_kilcoyne_ade_2006, title={Solid state effects in the NEXAFS spectra of alkane-based van der Waals crystals: Breakdown of molecular model}, volume={430}, ISSN={["1873-4448"]}, DOI={10.1016/j.cplett.2006.08.110}, abstractNote={Experimental data conclusively shows that the weak van der Waals interactions between alkane molecules, <1.5% the strength of covalent bonding on a per carbon atom basis, modify the carbon 1s near edge X-ray absorption fine structure (NEXAFS) spectrum significantly in ordered solids, both in intensity, spectral shape, peak position, and dichroic signature. This constitutes a further breakdown of the ‘building block’ model, or, more precisely, even a molecular model in interpreting NEXAFS spectra. These observations have significant implications for the interpretation and use of NEXAFS spectra from any crystalline or semi-crystalline macromolecules, small molecules, or other weakly interacting systems.}, number={4-6}, journal={CHEMICAL PHYSICS LETTERS}, author={Zou, Y. and Araki, T. and Appel, G. and Kilcoyne, A. L. D. and Ade, H.}, year={2006}, month={Oct}, pages={287–292} }
 @article{wang_rafailovich_sokolov_gersappe_araki_zou_kilcoyne_ade_marom_lustiger_2006, title={Substrate effect on the melting temperature of thin polyethylene films}, volume={96}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.96.028303}, abstractNote={Strong dependence of the crystal orientation, morphology, and melting temperature (Tm) on the substrate is observed in the semicrystalline polyethylene thin films. The Tm decreases with the film thickness decrease when the film is thinner than a certain critical thickness, and the magnitude of the depression increases with increasing surface interaction. We attribute the large Tm depression to the decrease in the overall free energy on melting, which is caused by the substrate attraction force to the chains that competes against the interchain force which drives the chains to crystallization.}, number={2}, journal={PHYSICAL REVIEW LETTERS}, author={Wang, Y and Rafailovich, M and Sokolov, J and Gersappe, D and Araki, T and Zou, Y and Kilcoyne, ADL and Ade, H and Marom, G and Lustiger, A}, year={2006}, month={Jan} }
 @article{fujii_armes_araki_ade_2005, title={Direct imaging and spectroscopic characterization of stimulus-responsive microgels}, volume={127}, ISSN={["1520-5126"]}, DOI={10.1021/ja056589p}, abstractNote={Scanning transmission X-ray microscopy has been employed to visualize pH-responsive acid-swellable microgel particles directly in their swollen state in aqueous acidic solution. Moreover, NEXAFS studies confirm that the nitrogen atoms of these cationic microgel particles are completely protonated at low pH.}, number={48}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Fujii, S and Armes, SP and Araki, T and Ade, H}, year={2005}, month={Dec}, pages={16808–16809} }
 @article{harton_koga_stevie_araki_ade_2005, title={Investigation of blend miscibility of a ternary PS/PCHMA/PMMA system using SIMS and mean-field theory}, volume={38}, ISSN={["1520-5835"]}, DOI={10.1021/ma051595r}, abstractNote={Poly(cyclohexyl methacrylate) (PCHMA) and polystyrene (PS) are miscible with each other, but each is highly immiscible with PMMA. Identifiable by the asymmetries in the binary mean-field interaction parameters χ, PS preferentially segregates to the PCHMA/PMMA interface. Secondary ion mass spectrometry was used to provide real-space depth profiles of deuterated PS (dPS) in a miscible blend with PCHMA. The initial dPS concentration was varied from 5 to 20% (v/v), and the blend film was annealed at 150 °C on a film of PMMA for 42 h. X-ray reflectometry was used to determine the interfacial width between PCHMA and PMMA at 150 °C. Using self-consistent mean-field theory, good agreement was found between the experimental and theoretical interfacial excess Z* of dPS at each concentration. Because of their similar glass transition temperatures (∼100 °C for PS and PCHMA) and the ability of PS and PCHMA to be controllably synthesized with low polydispersities, we anticipate this blend to be a model system for futur...}, number={25}, journal={MACROMOLECULES}, author={Harton, SE and Koga, T and Stevie, FA and Araki, T and Ade, H}, year={2005}, month={Dec}, pages={10511–10515} }
 @article{yokoyama_ishii_matsuie_kanai_ito_fujimori_araki_ouchi_seki_2005, title={Neat Alq(3) thin film and metal/Alq(3) interfaces studied by NEXAFS spectroscopy}, volume={152}, ISSN={["0379-6779"]}, DOI={10.1016/j.synthmet.2005.07.108}, abstractNote={Thin film of Alq3 and its interfaces with various metals (K, Li, Ca, Al)/Alq3 and the Al/LiF/Alq3 interface were investigated using NEXAFS spectroscopy. The assignments of structures in NEXAFS spectra at the C, N and O K-edges were performed using theoretical calculations taking account of the core-excitonic effect. The NEXAFS spectra at the three edges are well reproduced by the simulated results. The spectra at the N and O K-edges of Alq3 are similar to the partial density of unoccupied states (PDOUS) of the ground state, but the spectrum at the C K-edge is different from the PDOUS of ground state due to the core-excitonic effect. The present study is the first trial of the detailed analysis of the C K-edge spectrum of Alq3. The spectral changes at the metal/Alq3 and Al/LiF/Alq3 interface were found to depend on the metal. By the comparison with the theoretical simulations based on the 1:1 metal-Alq3 complex, we found that the electron transfer and orbital overlap occur at the interfaces of K/Alq3 and Li/Alq3, while the observed changes at the Ca/Alq3 and Al/Alq3 interfaces could not be understood by the simulated results. At the LiF/Alq3 interface, we observed the spectral changes which may result from some chemical interaction. Some of the spectral changes at Al/LiF/Alq3 interface differ from those of Al/Alq3 interface, indicating chemical interaction specific for the co-existence of Al, LiF, and Alq3.}, number={1-3}, journal={SYNTHETIC METALS}, author={Yokoyama, T and Ishii, H and Matsuie, N and Kanai, K and Ito, E and Fujimori, A and Araki, T and Ouchi, Y and Seki, K}, year={2005}, month={Sep}, pages={277–280} }
 @article{wang_araki_ade_2005, title={Soft x-ray resonant reflectivity of low-Z material thin films}, volume={87}, ISSN={["1077-3118"]}, DOI={10.1063/1.2136353}, abstractNote={Soft x-ray resonant reflectivity, a method for low-Z materials that combines aspects of neutron reflectivity and x-ray reflectivity, is presented. Resonant reflectivity provides enhanced and selective sensitivity to specific chemical moieties near the absorption edges of constituent elements and was demonstrated through the characterization of a bilayer polymer thin film. The relative reflectivity of a particular interface could be tuned by adjusting the incident photon energy near the carbon 1s absorption edge. The resulting chemical specificity is analogous to using deuteration as a tracer or marker in neutron reflectivity, but without requiring special sample synthesis or preparation.}, number={21}, journal={APPLIED PHYSICS LETTERS}, author={Wang, C and Araki, T and Ade, H}, year={2005}, month={Nov} }