NSF Award
2404431
With support from the Environmental Chemical Sciences Program in the Division of Chemistry, Professors Yue Zhang and Garrett McKay at Texas A&M University will study the molecular-level composition and behavior of light absorbing compounds in atmospheric brown carbon (BrC). Specifically, the study will investigate the role of charge-transfer chromophores, which involves intra- or intermolecular interactions between light absorbing moieties. Atmospheric BrC has increasingly been recognized as an important regulator of Earth’s climate, but the role of charge-transfer chromophores remains incompletely understood. This project aims to address this knowledge gap by systematically examining the charge-transfer chromophores in the BrC using interdisciplinary methods and advanced analytical instrumentation. Targeted mentorship of underrepresented groups at different levels will be trained as next-generation STEM researchers. Knowledge gained from this project will also be shared with the general public through outreach programs such as Aggieland Saturday and K-12 science lectures that the PIs routinely organize.<br/><br/>This project will systematically examine the molecular composition and behavior of chromophores in atmospheric BrC to provide mechanistic understanding of their light absorption properties. First, the team will use chamber reactions to produce BrC from primary and secondary sources, characterizing the aerosol chemical composition in real time using advanced mass spectrometry approaches including chemical ionization mass spectrometry. Second, filter extracted BrC will be further characterized by high resolution mass spectrometry coupled to absorbance detection to identify key chromophores in the atmospheric BrC. Molecular information from mass spectrometry will be corroborated by studying the impact of pH, redox status, and molecular size on the optical properties of filter-extracted BrC. Third, studies of the photostability of filter-extracted BrC and their propensity to generate singlet oxygen will be conducted to better characterize its atmospheric aging. This project will improve mechanistic understanding of chromophores, key species altering light-absorption of many environmental systems, as well as the direct climate effects of aerosols.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
