Research

Our studies are generally motivated by the desire to understand the connections between biological and chemical interfaces and the atmosphere. We study chemical processes that occur on air-exposed surfaces, the chemistry of how organisms communicate, and atmospheric chemistry that affects human health. To achieve these goals, we also develop new ways to detect the chemical composition of complex environmental systems using cutting-edge instrumentation. 

Multiphase chemistry of complex organic films

The real environment is full of gas-solid and gas-liquid phase interfaces, and these processes influence our environment in many different ways. Atmospheric chemists have been interested in surface-mediated chemical reactions since the late 1980's, when this type of chemistry was found to play an important role in forming the Stratospheric Ozone Hole. While research has continued to illustrate the influence of heterogeneous chemistry on the composition of the atmospheric gas phase, questions about the the impact of multiphase reactions on the condensed (solid or liquid) phase remain. Many studies that have been completed thus far have probed just a single solid or liquid chemical component. Real environmental surfaces can contain thousands of compounds. Our group is pushing scientific knowledge forward in this area by increasing the chemical complexity of the interfaces, investigating dynamic alterations to surface film composition, and exploring the impact of reactive gas mixtures above organic surface films.

We are applying our experimental approaches to studying questions relevant to the chemistry of indoor environments, especially as they pertain to recent changes in disinfection behavior and air cleaning. We are interested in how disinfection processes could introduce new multiphase chemistry to indoor spaces and potentially transform the chemical exposure profile for those who inhabit the space. Our studies are fundamental in their approach and therefore can also educate our understanding of atmospheric aerosol particles, the inner surfaces of our lungs, the human skin surface, the ocean surface (air-sea interface), and other biospheric surfaces relevant to plants and insects. 

For more information about environmental chemistry at gas-liquid interfaces, see the tutorial book chapter, "Gas-Liquid Interfaces in the Atmosphere: Impacts, Complexity, and Challenges" by Prof. Collins and Prof. Vicki Grassian (UC San Diego). 


analytical techniques for environmental Chemistry

We use a variety of analytical techniques in our group, but our research is centered mostly around using mass spectrometry to study chemically complex environmental systems. Samples may be generated through laboratory experiments or may be collected from field sites out in the real world. Our lab is also developing new ways to introduce samples to mass spectrometers. Bucknell has an impressive suite of instrumentation that we use to conduct our research, including:

Liquid Chromatograph/Ion Mobility Quadrupole-Time-of-Flight Tandem Mass Spectrometer (Agilent 6560; LC-IM-Q-ToF)

Liquid Chromatograph/High-Resolution Mass Spectrometer (Thermo Scientific Exactive Orbitrap; LC-HRMS)

Thermal Desorption coupled to Gas Chromatograph/Mass Spectrometer (Agilent 8860/5977B; TD-GC-MS)

Atmospheric Solids Analysis Probe coupled to Quadrupole Mass Spectrometer (Advion expressIon-L; ASAP-MS)


--Collaborations--

'Molecules to Mating': Chemical Signaling in Fireflies

While many people are familiar with the flashing signal produced by nocturnal fireflies in the summer, many related firefly species lack the ability to produce light and use other means to find mates. In a multi-disciplinary collaboration with Prof. Lower (Bucknell, Biology) and Prof. Pask (Middlebury College, Biology), our group is working to understand the nature of volatile and surface-bound chemical signaling agents in fireflies.