Carnegie Mellon University Department of Chemistry
photo of Ryan Sullivan

Ryan Sullivan

Assistant Professor of Chemistry & Mechanical Engineering

Carnegie Mellon University

Offices: DH 2111, MI 832

Phone: (412) 268-8462


ORCID: 0000-0003-0701-7158
ResearcherID: B-4674-2008

The Center for Atmospheric Particle Studies

Faculty & Research

Ryan Sullivan

Assistant Professor of Chemistry & Mechanical Engineering

Research Areas

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 Assistant Professor of Chemistry and Mechanical Engineering at Carnegie Mellon University, beginning in January 2012. 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 nucleation both warm cloud droplets and ice crystals, thus altering cloud properties and the Earth's climate. These research endeavours 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, energy balance, cloud nucleation, biogeochemical cycles, and other important climate feedbacks motivate our interest in increasing our understanding of the chemical behaviour 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.

Education and Appointments
Years Position or Degree
2012 Assistant Professor of Chemistry & Mechanical Engineering, Carnegie Mellon University
2009–2011 Post-Doctoral Fellow and Research Scientist, Colorado State University
2008 Ph.D., Chemistry, University of California, San Diego
2006 M.Sc., Chemistry, University of California, San Diego
2002 Hon. B.Sc., Chemistry, University of Toronto
Awards and Distinctions
Years Award
2016 NSF CAREER Award
Selected Publications

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

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

Gorkowski, K.; Beydoun, H.; Aboff, M.; Walker, J. S.; Reid, J. P.; Sullivan, R. C. Advanced aerosol optical tweezers chamber design to facilitate phase-separation and equilibration timescale experiments on complex droplets. Aerosol Sci. Technol. 2016, 50, 1327–1341, doi:10.1080/02786826.2016.1224317.

Polen, M.; Lawlis, E.; Sullivan, R. C. The unstable ice nucleation properties of Snomax® bacterial particles. J. Geophys. Res. Atmos. 2016, 121, 11,666-11,678, doi:10.1002/2016JD025251.

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. Sea spray aerosol as a unique source of ice nucleating particles. Proc. Natl. Acad. Sci. 2016, 113, 5797–5803, doi:10.1073/pnas.1514034112.

Saliba, G.; Subramanian, R.; Saleh, R.; Ahern, A. T.; Lipsky, E. M.; Tasoglou, A.; Sullivan, R. C.; Bhandari, J.; Mazzoleni, C.; Robinson, A. L. Optical properties of black carbon in cookstove emissions coated with secondary organic aerosols: Measurements and modeling. Aerosol Sci. Technol. 2016, 50, 1264–1276, doi:10.1080/02786826.2016.1225947.

Ye, Q.; Robinson, E. S.; Ding, X.; Ye, P.; Sullivan, R. C.; Donahue, N. M. Mixing of secondary organic aerosols versus relative humidity. Proc. Natl. Acad. Sci. 2016, 113, 12649–12654, doi:10.1073/pnas.1604536113.

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.; Kreidenweis, S. M. Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles. Atmos. Chem. Phys. 2015, 15, 393–409, doi:10.5194/acp-15-393-2015.

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.; Robinson, A. L. Brownness of organics in aerosols from biomass burning linked to their black carbon content. Nat. Geosci. 2014, 7, 647–650, doi:10.1038/ngeo2220.

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. Dust and biological aerosols from the Sahara and Asia influence precipitation in the western U.S. Science 2013, 339, 1572–1578, doi:10.1126/science.1227279.

Sullivan, R. C.; Miñambres, L.; DeMott, P. J.; Prenni, A. J.; Carrico, C. M.; Levin, E. J. T.; Kreidenweis, S. M. Chemical processing does not always impair heterogeneous ice nucleation of mineral dust particles. Geophys. Res. Lett. 2010, 37, L24805, doi:10.1029/2010GL045540.

Sullivan, R. C.; Moore, M. J. K.; Petters, M. D.; Kreidenweis, S. M.; Roberts, G. C.; Prather, K. A. Effect of chemical mixing state on the hygroscopicity and cloud nucleation properties of calcium mineral dust particles. Atmos. Chem. Phys. 2009, 9, 3303–3316.

Sullivan, R. C.; Moore, M. J. K.; Petters, M. D.; Kreidenweis, S. M.; Roberts, G. C.; Prather, K. A. Timescale for hygroscopic conversion of calcite mineral particles through heterogeneous reaction with nitric acid. Phys. Chem. Chem. Phys. 2009, 11, 7826, doi:10.1039/b904217b.

Sullivan, R. C.; Guazzotti, S.; Sodeman, D. A.; Prather, K. A. Direct observations of the atmospheric processing of Asian mineral dust. Atmos. Chem. Phys. 2007, 7, 1213–1226.