Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder

Eleanor C. Browne

Research Interests

My group is interested in developing instrumentation for measuring gases and aerosols in the atmosphere and in using this instrumentation to investigate how atmospheric processing affects the chemical composition of gases and aerosols. The group is specifically interested in organonitrogen and organosilicon compounds and investigates the fate of these compounds using laboratory and field measurements. Current work focuses on understanding the role of organonitrogen in new particle formation and growth, and in nitrogen deposition. The organosilicon work focuses on constraining the fate of organosilicon compounds that are found in personal care products and preferentially partition to the atmosphere. Our current instrument development work focuses on novel techniques for the fragment-free characterization of aerosol.

Current Research

Ambient Ion Chemistry

Atmospheric ions control the electrical properties of the atmosphere, influence chemical composition via ion-molecule and/or ion-catalyzed reactions, and affect new particle formation. Understanding the role of ions in these processes requires knowledge of ionic chemical composition.  Due to the low concentration of ions, chemical composition measurements have historically been challenging. Recent advances in mass spectrometry, such as the atmospheric pressure interface time-of-flight mass spectrometer (APi-TOF), are now making these measurements more feasible. We study the chemistry of ambient ions through field measurements to understand present day ambient atmosphere and laboratory experiments that simulate other planetary atmospheres such as early Earth and Titan.

Organosilicon Chemistry

Several million tons of organosilicon compounds, most notably volatile methyl siloxanes (VMS), are manufactured annually for use in a variety of applications including personal care products and adhesives. Despite estimates that over 90 percent of VMS environmental loading is present in the atmosphere, the multigenerational chemistry of VMS remains poorly constrained. We use an environmental simulation chamber to simulate atmospheric oxidation of siloxanes so we can detect the products of atmospheric reactions with these compounds as well as gather information about rate constants and reaction pathways of these reactions. 

Instrument Development

Aerosols (fine particulate matter suspended in air) affect human health and the Earth’s radiative balance. Improving our knowledge of how aerosols affect climate and health requires measurements of aerosol chemical composition in order to improve our understanding of aerosol sources and sinks. These measurements, however, are analytically challenging as the aerosols with the greatest impacts on health and climate are submicron in diameter, present at concentrations of μg or less per cubic meter of air, and are composed of both inorganic and organic compounds. Furthermore, the composition of the organic fraction is complex, consisting of thousands of compounds, including those that are chemically and thermally labile. The group is currently working on developing a novel measurement technique that combines laser desorption with chemical ionization mass spectrometry.



histogram

Average mass spectrum of the five CxH2x+nNH+ families with double bond equivalencies (DBE) ranging from 0 to 4 during a laboratory experiment investigating ion formation in CH4/N2 mixtures that approximate Titan’s atmosphere. As the ion mass increases the ions become increasingly unsaturated, suggesting that aerosol precursors are highly unsaturated compounds. Image: Berry et al. 2019

Honors and Awards

  • American Society for Mass Spectrometry Research Award (2019)
  • NOAA Climate and Global Change Postdoctoral Fellowship (2012-2014)
  • NASA Earth Systems Science Fellowship (2010-2012)