@article{rothfuss_petters_champion_grieshop_petters_2019, title={Characterization of a dimer preparation method for nanoscale organic aerosol}, volume={53}, ISSN={["1521-7388"]}, url={https://doi.org/10.1080/02786826.2019.1623379}, DOI={10.1080/02786826.2019.1623379}, abstractNote={Abstract Nanoscale dimers have application in studies of aerosol physicochemical properties such as aerosol viscosity. These particle dimers can be synthesized using the dual tandem differential mobility analyzer (DTDMA) technique, wherein oppositely charged particle streams coagulate to form dimers that can be isolated using electrostatic filtration. Although some characterization of the technique has been published, a detailed thesis on the modes and theory of operation has remained outside the scope of prior work. Here, we present new experimental data characterizing the output DTDMA size distribution and the physical processes underlying its apparent modes. Key experimental limitations for both general applications and for viscosity measurements are identified and quantified in six distinct types of DTDMA experiments. The primary consideration is the production of an adequate number of dimers, which typically requires high mobility-selected number concentration in the range 25,000–100,000 cm−3. The requisite concentration threshold depends upon the rate of spontaneous monomer decharging, which arises predominately from interactions of the aerosol with ionizing radiation within the coagulation chamber and is instrument location dependent. Lead shielding of the coagulation chamber reduced the first-order decharging constant from ∼2.0 × 10−5 s−1 to ∼0.8 × 10−5 s−1 in our laboratory. Dimer production at monomer diameters less than 40 nm is hindered by low bipolar charging efficiency. Results from the characterization experiments shed light on design considerations for general applications and for characterization of viscous aerosol phase transitions. Copyright © 2019 American Association for Aerosol Research}, number={9}, journal={AEROSOL SCIENCE AND TECHNOLOGY}, publisher={Informa UK Limited}, author={Rothfuss, Nicholas E. and Petters, Sarah S. and Champion, Wyatt M. and Grieshop, Andrew P. and Petters, Markus D.}, year={2019}, month={Sep}, pages={998–1011} }
 @article{petters_kreidenweis_grieshop_ziemann_petters_2019, title={Temperature- and Humidity-Dependent Phase States of Secondary Organic Aerosols}, volume={46}, ISSN={["1944-8007"]}, url={https://doi.org/10.1029/2018GL080563}, DOI={10.1029/2018GL080563}, abstractNote={AbstractViscosity of monoterpene‐derived secondary organic aerosols (SOAs) as a function of temperature and relative humidity (RH), and dry SOA glass transition temperatures are reported. Viscosity was measured using coalescence time scales of synthesized 100 nm dimers. Dry temperature‐dependent SOA viscosity was similar to that of citric acid, coal tar pitch, and sorbitol. The temperature where dry viscosity was 106 Pa·s varied between 14 and 36 °C and extrapolated glass transition varied between −10 and 20 °C (±10 °C). Mass fragment f44 obtained with an Aerosol Chemical Speciation Monitor was anticorrelated with viscosity. Viscosity of humidified Δ3‐carene and α‐pinene SOAs exceeded 106 Pa·s for all subsaturated RHs at temperatures <0 and –5 °C, respectively. Steep viscosity isopleths at 106 Pa·s were traced for these across (temperature, RH) conditions ranging from (approximately −5 °C, 100%) and (approximately 36 °C, 0%). Differences in composition and thus hygroscopicity can shift humidified viscosity isopleths for SOAs at cold tropospheric temperatures.}, number={2}, journal={GEOPHYSICAL RESEARCH LETTERS}, publisher={American Geophysical Union (AGU)}, author={Petters, Sarah S. and Kreidenweis, Sonia M. and Grieshop, Andrew P. and Ziemann, Paul J. and Petters, Markus D.}, year={2019}, month={Jan}, pages={1005–1013} }
 @article{dawson_petters_meskhidze_petters_kreidenweis_2016, title={Hygroscopic growth and cloud droplet activation of xanthan gum as a proxy for marine hydrogels}, volume={121}, ISSN={["2169-8996"]}, DOI={10.1002/2016jd025143}, abstractNote={AbstractKnowledge of the physical characteristics and chemical composition of marine organic aerosols is needed for the quantification of their effects on cloud microphysical processes and solar radiative transfer. Here we use xanthan gum (XG)—a bacterial biopolymer—as a proxy for marine hydrogels. Measurements were performed for pure XG particles and mixtures of XG with sodium chloride, calcium nitrate, and calcium carbonate. The aerosol hygroscopicity parameter (κ) is derived from hygroscopic growth factor measurements (κgf) at variable water activity (aw) and from cloud condensation nuclei activation efficiency (κccn). The Zdanovskii, Stokes, and Robinson (ZSR) hygroscopicity parameter derived for multicomponent systems (κmix, sol) is used to compare measurements of κgf and κccn. Pure XG shows close agreement of κgf (at aw = 0.9) and κccn of 0.09 and 0.10, respectively. Adding salts to the system results in deviations of κgf (at aw = 0.9) from κccn. The measured κgf and ZSR‐derived hygroscopicity parameter (κmix, sol) values for different solutions show close agreement at aw > 0.9, while κgf is lower in comparison to κmix, sol at aw < 0.9. The differences between predicted κmix, sol and measured κgf and κccn values are explained by the effects of hydration and presence of salt ions on the structure of the polymer networks. Results from this study imply that at supersaturations of 0.1 and 0.5%, the presence of 30% sea salt by mass can reduce the activation diameter of pure primary marine organic aerosols from 257 to 156 nm and from 87 to 53 nm, respectively.}, number={19}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Dawson, K. W. and Petters, M. D. and Meskhidze, N. and Petters, S. Suda and Kreidenweis, S. M.}, year={2016}, month={Oct}, pages={11803–11818} }
 @article{nakao_suda_camp_petters_kreidenweis_2014, title={Droplet activation of wet particles: development of the Wet CCN approach}, volume={7}, number={7}, journal={Atmospheric Measurement Techniques}, author={Nakao, S. and Suda, S. R. and Camp, M. and Petters, M. D. and Kreidenweis, S. M.}, year={2014}, pages={2227–2241} }
 @article{suda_petters_yeh_strollo_matsunaga_faulhaber_ziemann_prenni_carrico_sullivan_et al._2014, title={Influence of Functional Groups on Organic Aerosol Cloud Condensation Nucleus Activity}, volume={48}, ISSN={["1520-5851"]}, DOI={10.1021/es502147y}, abstractNote={Organic aerosols in the atmosphere are composed of a wide variety of species, reflecting the multitude of sources and growth processes of these particles. Especially challenging is predicting how these particles act as cloud condensation nuclei (CCN). Previous studies have characterized the CCN efficiency for organic compounds in terms of a hygroscopicity parameter, κ. Here we extend these studies by systematically testing the influence of the number and location of molecular functional groups on the hygroscopicity of organic aerosols. Organic compounds synthesized via gas-phase and liquid-phase reactions were characterized by high-performance liquid chromatography coupled with scanning flow CCN analysis and thermal desorption particle beam mass spectrometry. These experiments quantified changes in κ with the addition of one or more functional groups to otherwise similar molecules. The increase in κ per group decreased in the following order: hydroxyl ≫ carboxyl > hydroperoxide > nitrate ≫ methylene (where nitrate and methylene produced negative effects, and hydroperoxide and nitrate groups produced the smallest absolute effects). Our results contribute to a mechanistic understanding of chemical aging and will help guide input and parametrization choices in models relying on simplified treatments such as the atomic oxygen:carbon ratio to predict the evolution of organic aerosol hygroscopicity.}, number={17}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Suda, Sarah R. and Petters, Markus D. and Yeh, Geoffrey K. and Strollo, Christen and Matsunaga, Aiko and Faulhaber, Annelise and Ziemann, Paul J. and Prenni, Anthony J. and Carrico, Christian M. and Sullivan, Ryan C. and et al.}, year={2014}, month={Sep}, pages={10182–10190} }
 @article{nguyen_petters_suda_guo_weber_carlton_2014, title={Trends in particle-phase liquid water during the Southern Oxidant and Aerosol Study}, volume={14}, number={20}, journal={Atmospheric Chemistry and Physics}, author={Nguyen, T. K. V. and Petters, M. D. and Suda, S. R. and Guo, H. and Weber, R. J. and Carlton, A. G.}, year={2014}, pages={10911–10930} }
 @article{suda_petters_2013, title={Accurate Determination of Aerosol Activity Coefficients at Relative Humidities up to 99% Using the Hygroscopicity Tandem Differential Mobility Analyzer Technique}, volume={47}, ISSN={["1521-7388"]}, DOI={10.1080/02786826.2013.807906}, abstractNote={Aerosol water content plays an important role in aqueous phase reactions, in controlling visibility, and in cloud formation processes. One way to quantify aerosol water content is to measure hygroscopic growth using the hygroscopicity tandem differential mobility analyzer (HTDMA) technique. However, the HTDMA technique becomes less reliable at relative humidity (RH) >90% due to the difficulty of controlling temperature and RH inside the second DMA. For this study, we have designed and implemented a new HTDMA system with improved temperature and RH control. Temperature stability in the second DMA was achieved to ±0.02°C tolerance by implementing active control using thermoelectric heat exchangers and PID control loops. The DMA size resolution was increased by operating high-flow DMA columns at a sheath:sample flow ratio of 15:0.5. This improved size resolution allowed for improving the accuracy of the RH sensors by interspersing ammonium sulfate reference scans at high frequency. We present growth factor data for pure compounds at RH up to 99% and compare the data to theoretical values and to available bulk water activity data. With this HTDMA instrument and method, the osmotic coefficients of spherical, nonvolatile aerosols of known composition between 30 and 200 nm in diameter can be determined within ±20%. We expect that data from this instrument will lead to an improvement of aerosol water content models by contributing to the understanding of aerosol water uptake at high RH. Copyright 2013 American Association for Aerosol Research}, number={9}, journal={AEROSOL SCIENCE AND TECHNOLOGY}, author={Suda, Sarah R. and Petters, Markus D.}, year={2013}, month={Sep}, pages={991–1000} }
 @article{meskhidze_petters_tsigaridis_bates_o'dowd_reid_lewis_gantt_anguelova_bhave_et al._2013, title={Production mechanisms, number concentration, size distribution, chemical composition, and optical properties of sea spray aerosols}, volume={14}, number={4}, journal={Atmospheric Science Letters}, author={Meskhidze, N. and Petters, M. D. and Tsigaridis, K. and Bates, T. and O'Dowd, C. and Reid, J. and Lewis, E. R. and Gantt, B. and Anguelova, M. D. and Bhave, P. V. and et al.}, year={2013}, pages={207–213} }
 @inproceedings{petters_suda_christensen_2013, title={The role of dynamic surface tension in cloud droplet activation}, volume={1527}, booktitle={Nucleation and atmospheric aerosols}, author={Petters, M. D. and Suda, S. R. and Christensen, S. I.}, year={2013}, pages={801–807} }
 @article{suda_petters_matsunaga_sullivan_ziemann_kreidenweis_2012, title={Hygroscopicity frequency distributions of secondary organic aerosols}, volume={117}, journal={Journal of Geophysical Research. Atmospheres (Online)}, author={Suda, S. R. and Petters, M. D. and Matsunaga, A. and Sullivan, R. C. and Ziemann, P. J. and Kreidenweis, S. M.}, year={2012} }