Carnegie Mellon University

Ryan Sullivan

Ryan Sullivan

Professor, Chemistry
Professor, Mechanical Engineering
Associate Director, Institute for Green Science


2008     Ph.D., Chemistry, University of California, San Diego


Atmospheric chemistry, aerosol instrumentation, single-particle analysis, mass spectrometry, laser spectroscopy, heterogeneous chemistry, combustion, particle hygroscopicity, cloud nucleation, aerosol-cloud-climate interactions


Dr. Ryan Sullivan is an Associate Professor of Chemistry and Mechanical Engineering at Carnegie Mellon University. He is also a faculty member in the Centre for Atmospheric Particle Studies.

Ryan Sullivan has a background in atmospheric and analytical chemistry, single-particle analysis, heterogeneous kinetics, and cloud nucleation research. His research interests include the development of improved aircraft-deployable analytical instrumentation to characterize individual particles in the atmosphere in real-time. These instruments are used to investigate the physicochemical properties of atmospheric particles emitted and produced from a variety of sources, the chemical processes they experience during atmospheric transport, and how these processes modify the ability of particles to nucleate both cloud droplets and ice crystals, thus altering cloud properties and the Earth’s climate. These research endeavors involve equal parts instrument development, laboratory experiments, and field measurements.

Particles in the atmosphere exist in a wide variety of shapes, sizes, and chemical compositions. These properties are highly dynamic, constantly evolving as the particles respond to changes in their gas-phase environment. This makes the study of atmospheric aerosol particles both challenging and fascinating. The important but still poorly understood roles that particles play in influencing air quality, the atmosphere’s chemical balance, cloud nucleation, energy balance, biogeochemical cycles, and other important climate feedbacks motivate our interest in improving our understanding of the chemical behavior of particles in our atmosphere. Our comprehension of these processes is currently limited by the instrumentation available to measure key properties of individual atmospheric particles.

We investigate these important physicochemical particle properties using custom single-particle instruments that allow us to rapidly characterize atmospheric aerosols in real-time, one particle after another. We are developing improved analytical methods to measure individual particles using laser ablation mass spectrometry, and laser spectroscopy. These new instruments are utilized in both laboratory studies and field experiments (from ground, ship, and aircraft sampling platforms) to determine the kinetics and products of a variety of atmospheric chemical aging processes (e.g. heterogeneous reaction, aqueous-phase chemistry, gas-to-particle conversion, photochemistry, new particle formation). Small cloud simulation chambers are also used to determine the ability of the chemically processed particles to nucleate both warm cloud droplets, and ice crystals via heterogeneous ice nucleation.

Single-particle analysis is an important analytical tool that allows us to determine how the myriad chemical constituents are distributed between individual particles (mixing state). As all particle properties (interaction with radiation, heterogeneous kinetics, hygroscopicity, heterogeneous ice nucleation, toxicity, etc.) are dictated by each particle’s unique size and chemical composition, single-particle analysis is required to determine the exact relationships between the sources of atmospheric particles, their size and chemical composition, how they behave chemically in the atmosphere, and what their resulting important environmental effects are.


Production of N2O5 and ClNO2 through Nocturnal Processing of Biomass-Burning Aerosol
Ahern, A. T.; Goldberger, L.; Jahl, L.; Thornton, J.; Sullivan, R. C. Environ. Sci. Technol. 201852, 550–559, doi:10.1021/acs.est.7b04386.

Following Particle-Particle Mixing in Atmospheric Secondary Organic Aerosols by Using Isotopically Labeled Terpenes
Ye, Q.; Upshur, M. A.; Robinson, E. S.; Geiger, F. M.; Sullivan, R. C.; Thomson, R. J.; Donahue, N. M. Chem 20184, 318–333, doi:10.1016/j.chempr.2017.12.008.

A new multicomponent heterogeneous ice nucleation model and its application to Snomax bacterial particles and a Snomax–illite mineral particle mixture
Beydoun, H.; Polen, M.; Sullivan, R. C. Atmos. Chem. Phys. 201717, 13545–13557, doi:10.5194/acp-17-13545-2017.

Emulsified and Liquid–Liquid Phase-Separated States of α-Pinene Secondary Organic Aerosol Determined Using Aerosol Optical Tweezers
Gorkowski, K.; Donahue, N. M.; Sullivan, R. C. Environ. Sci. Technol.201751, 12154–12163, doi:10.1021/acs.est.7b03250.

Modeling the contributions of global air temperature, synoptic-scale phenomena and soil moisture to near-surface static energy variability using artificial neural networks.
Pryor, S. C., Sullivan, R. C., & Schoof, J. T. (2017). Atmospheric Chemistry and Physics, 17(23), 14457-14471.

Effect of secondary organic aerosol coating thickness on the real-time detection and characterization of biomass-burning soot by two particle mass spectrometers
Ahern, A. T.; Subramanian, R.; Saliba, G.; Lipsky, E. M.; Donahue, N. M.; Sullivan, R. C. Atmos. Meas. Tech. 20169, 6117–6137, doi:10.5194/amt-9-6117-2016.

Effect of particle surface area on ice active site densities retrieved from droplet freezing spectra
Beydoun, H.; Polen, M.; Sullivan, R. C. Atmos. Chem. Phys. 201616, 13359–13378, doi:10.5194/acp-16-13359-2016.

Advanced aerosol optical tweezers chamber design to facilitate phase-separation and equilibration timescale experiments on complex droplets
Gorkowski, K.; Beydoun, H.; Aboff, M.; Walker, J. S.; Reid, J. P.; Sullivan, R. C. Aerosol Sci. Technol. 201650, 1327–1341, doi:10.1080/02786826.2016.1224317.

The unstable ice nucleation properties of Snomax® bacterial particles
Polen, M.; Lawlis, E.; Sullivan, R. C. J. Geophys. Res. Atmos. 2016121, 11,666-11,678, doi:10.1002/2016JD025251.

Sea spray aerosol as a unique source of ice nucleating particles
DeMott, P. J.; Hill, T. C. J.; McCluskey, C. S.; Prather, K. A.; Collins, D. B.; Sullivan, R. C.; Ruppel, M. J.; Mason, R. H.; Irish, V. E.; Lee, T.; Hwang, C. Y.; Rhee, T. S.; Snider, J. R.; McMeeking, G. R.; Dhaniyala, S.; Lewis, E. R.; Wentzell, J. J. B.; Abbatt, J.; Lee, C.; Sultana, C. M.; Ault, A. P.; Axson, J. L.; Diaz Martinez, M.; Venero, I.; Santos-Figueroa, G.; Stokes, M. D.; Deane, G. B.; Mayol-Bracero, O. L.; Grassian, V. H.; Bertram, T. H.; Bertram, A. K.; Moffett, B. F.; Franc, G. D., Proc. Natl. Acad. Sci. U. S. A., 2015, doi:10.1073/pnas.1514034112.

Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles
DeMott, P. J., Prenni, A. J., McMeeking, G. R., Sullivan, R. C., Petters, M. D., Tobo, Y., Niemand, M., Möhler, O., Snider, J. R., Wang, Z. and Kreidenweis, S. M., Atmospheric Chemistry and Physics, 15(1), 393–409, doi:10.5194/acp-15-393-2015, 2015.

Brownness of organics in aerosols from biomass burning linked to their black carbon content
Saleh, R., Robinson, E. S., Tkacik, D. S., Ahern, A. T., Liu, S., Aiken, A. C., Sullivan, R. C., Presto, A. A., Dubey, M. K., Yokelson, R. J., Donahue, N. M. and Robinson, A. L., Nature Geoscience, 7(9), 647–650, doi:10.1038/ngeo2220, 2014.

Trace gas emissions from combustion of peat, crop residue, domestic biofuels, grasses, and other fuels: configuration and Fourier transform infrared (FTIR) component of the fourth Fire Lab at Missoula Experiment (FLAME-4)
Stockwell, C. E., Yokelson, R. J., Kreidenweis, S. M., Robinson, A. L., DeMott, P. J., Sullivan, R. C., Reardon, J., Ryan, K. C., Griffith, D. W. T. and Stevens, L., Atmospheric Chemistry and Physics, 14(18), 9727–9754, doi:10.5194/acp-14-9727-2014, 2014.

Influence of functional groups on organic aerosol cloud condensation nucleus activity
Suda, S. R., Petters, M. D., Yeh, G. K., Strollo, C., Matsunaga, A., Faulhaber, A., Ziemann, P. J., Prenni, A. J., Carrico, C. M., Sullivan, R. C. and Kreidenweis, S. M., Environmental Science & Technology, 48(17), 10182–90, doi:10.1021/es502147y, 2014.

Dust and biological aerosols from the Sahara and Asia influence precipitation in the western U.S.
Creamean, J. M.; Suski, K. J.; Rosenfeld, D.; Cazorla, A.; Demott, P. J.; Sullivan, R. C.; White, A. B.; Ralph, F. M.; Minnis, P.; Comstock, J. M.; Tomlinson, J. M.; Prather, K. A. Science 2013339, 1572–1578, doi:10.1126/science.1227279.

Bringing the ocean into the laboratory to probe the chemical complexity of sea spray aerosol
Prather, K. A., Bertram, T. H., Grassian, V. H., Deane, G. B., Stokes, M. D., Demott, P. J., Aluwihare, L. I., Palenik, B. P., Azam, F., Seinfeld, J. H., Moffet, R. C., Molina, M. J., Cappa, C. D., Geiger, F. M., Roberts, G. C., Russell, L. M., Ault, A. P., Baltrusaitis, J., Collins, D. B., Corrigan, C. E., Cuadra-Rodriguez, L. A., Ebben, C. J., Forestieri, S. D., Guasco, T. L., Hersey, S. P., Kim, M. J., Lambert, W. F., Modini, R. L., Mui, W., Pedler, B. E., Ruppel, M. J., Ryder, O. S., Schoepp, N. G., Sullivan, R. C. and Zhao, D., Proceedings of the National Academy of Sciences of the United States of America, 110(19), 7550–5, doi:10.1073/pnas.1300262110, 2013.


Years Position
2017–present Associate Professor of Chemistry & Mechanical Engineering, Carnegie Mellon University
2012–2017 Assistant Professor of Chemistry & Mechanical Engineering, Carnegie Mellon University
2009–2011 Post-Doctoral Fellow and Research Scientist, Colorado State University

Awards and Distinctions

Years Award
2021 Senior Fellow in the Collegium Helveticum at ETH Zurich
2021 Fast Company's World Changing Ideas Awards
2021 Start-ups to Watch (Sudoc)
2020 Environmental Award, Carnegie Science Center
2019 Emerging Investigator in Environmental Science, “Environmental Science: Processes and Impacts,” Royal Society of Chemistry
2016 National Science Foundation Faculty Early Career Development Award (CAREER)
2015 Editors’ Citation for Excellence in Refereeing for Geophysical Research Letters
2011 Cozzarelli Prize, National Academy of Science USA
2009 Atmospheric Chemistry Colloquium for Emerging Senior Scientists (ACCESS) X
2004–2005 Department of Chemistry & Biochemistry Teaching Assistant Excellence Award, University of California, San Diego