Principal Investigator

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Raymond R. Tucker Distinguished InCEES Career Development Associate Professor
Dept. of Energy, Environmental, and Chemical Engineering

B.S., Saint Cloud State University
PhD, University of California - Berkeley


Google Scholar

Professor Williams' research interests focus on the exploration of the composition, chemistry, and physical properties of Earth's atmosphere to determine the role of biogenic and anthropogenic gases and particles in Earth's climate system. Current projects include the study of particle formation from biomass combustion, indoor air composition, secondary particle formation from photochemical aging, and novel instrumentation development.

Research and Teaching Award Highlights include:

  • NSF CAREER Award

  • U.S. EPA Early Career Award

  • Department Chair's Outstanding Teaching Award

  • Dean's Award for Excellence in Teaching

PhD Students


PhD Candidate
Energy, Environmental, and Chemical Engineering

B.S. Chemical Engineering '96, University of Arkansas
M.S. Chemical Engineering '99, University of Arkansas

After obtaining his Masters degree, Chris entered industry where he spent nearly 11 years in various engineering and supervisory roles. He resigned after those 11 years to entertain his dream of a PhD and a professorship. In 2011-2012, Chris taught Chemical Engineering classes as an adjunct professor confirming his path. His academic interests include transport phenomena and thermodynamics while his passions outside academia are spent as an avid cyclist and father. In the ACT Lab, Chris has worked to develop and test a volatility and hygroscopicity tandem differential mobility analyzer (VH-TDMA) for advanced measurement of aerosol physical properties.



PhD Candidate
Energy, Environmental, and Chemical Engineering

B.A. Chemistry ACS '13, Gustavus Adolphus College

Michael’s research interests revolve around studying the chemical composition of carbonaceous aerosols, and currently leads the development of the VAPS instrument. He has performed laboratory studies in the ACT lab utilizing the PAM oxidation chamber, as well as at Georgia Tech using an Environmental Chamber in collaboration with Dr. Nga Ng. He has performed field studies at East St. Louis, IL, at Jefferson St. Station in Atlanta, GA, and two indoor/outdoor field deployments at residential homes in St. Louis. In addition to instrument development, Michael has worked to advance our methods to employ Positive Matrix Factorization on a wide range of datasets and to archive our chemical source profiles from lab and field observations.



PhD Candidate
Energy, Environmental, and Chemical Engineering

B.S. Chemistry '14, College of William & Mary

Claire’s research interests include characterizing the oxidation chemistry of secondary organic and biomass burning aerosols, and to characterize the gas and particle composition of indoor air. She leads our development of a TAG instrument that quantifies the gas and particle fractions of semi-volatile organic molecules, a critical volatility range in the indoor environment as these chemical species experience dynamic phase partitioning amongst surface, particles, and the air, driven by human activity and building operation.

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NASA Earth and Space Science Graduate Fellow

PhD Candidate
Energy, Environmental, and Chemical Engineering

B.S. Physics ‘15, University of Nevada, Reno

Ben's current research focuses on fundamental radiative transfer properties of brown carbon aerosols emitted from smoldering wildfire fuels such as arctic peat. He continues to be involved in instrumentation development, including the construction of a 375 nm photoacoustic spectrometer and development and application of a new biomass burning chamber.  Ben is co-advised by Prof. Rajan Chakrabarty and also works in the AIR Lab at WashU.



NSF Graduate Research Fellow

PhD Candidate
Energy, Environmental, and Chemical Engineering

B.E. Chemical Engineering '14, Vanderbilt University

Audrey currently works on the development and deployment of lower-cost and portable air sampling instrumentation.  She has recently collaborated with WashU's Institute for Public Health and industry partners Aerodyne Research Inc. to deploy off-grid gas and particle monitors in Cap-Haitien, Haiti.  Audrey also collaborates with Prof. Jay Turner (WashU) on Haiti research and NIH-funded development of a portable volatile organic gas analyzer.

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Karolina Cysneiros de carvalho

PhD Candidate
Energy, Environmental, and Chemical Engineering

B.S. Chemical Engineering ‘18, Federal University of Pernambuco, Brazil





Sohyeon Jeon

PhD Candidate
Energy, Environmental, and Chemical Engineering

B.S. Environmental Engineering ‘17, Ewha Womans University, South Korea

M.S. Environmental Engineering ‘18, Ewha Womans University, South Korea



graduate student ALUMNI

Yaping Zhang (Ph.D.)

Dhruv Mitroo (Ph.D.)

Raul Martinez (M.S.)

Peter Mellott (M.S.)

Mayura Patankar (M.Eng.)

Ruijie Yu (M.Eng.)

Xiaochen Zuo (M.Eng.)



Munkhbayar Baasandorj (2014):  Research Scientist

Wei Zhou (2016-2017):  Tsinghua University, School of Environment (Advisor:  Prof. Jingkun Jiang)

Qiongqiong Wang (2017-2018):  Hong Kong University of Science & Technology, Department of Chemistry & Division of Environment (Advisor: Prof. Jian Zhen Yu)


Undergraduate Researchers


Izzi Clawson

Sydney Hornitschek

Remy Hutheesing

Connor Rutledge

Skyler Simon



Porter Abbey

Blake Actkinson

Jin Hwan Choi

Emma Cotter

Karolina Cysneiros De Carvalho

Austin Darmawan

Steven Dhawan

Nathan Ferree

Ben Fu

William Geyer

David Hagan


Ashley Hesterberg

Scarlett Li

Riley Martell

Michelle Molina

Chunsoo Park

Julianna Portelli

Purushottam Kumar

Charlie Rapp

Samantha Rosenthal

Taylor Smith

Ana Solorio

Jazmin Simpkins

Andrew Spitz 

Emma Streff

Eric Sussman

William Swanson

Oscar Tapia

Jessica Ulan

Pietro Vannucci

Daniel Watson

Alec Wilcosky

Stone Yan

Ruijie Yu

Xiaochen Zuo