The multiphase chemistry of condensed-phase materials has direct connections to issues in outdoor air quality, climate, and the indoor environment. These substrates, present as either particles or surface substrates, can be oxidized by gas-phase oxidants, become photochemically altered, and participate in partitioning processes with the overlying atmosphere. In the case of particles, aerosols can act as the sites for cloud formation and have deleterious effects on human health.
Attention is paid to studying these processes under conditions as close as possible to those in the environment, taking advantage of a range of on-line analytical tools, many of which are mass spectrometric. Examples of instrumentation includes the use of aerosol mass spectrometry (AMS), chemical ionization mass spectrometry (CIMS), proton-transfer-reaction mass spectrometry (PTR-MS) and direct analysis in real-time mass spectrometry (DART-MS). A particular focus of research in this field is the multiphase chemistry of wildfire smoke, with the potential for modification of the composition and optical properties of brown carbon aerosol.