Sunlight-Induced Nonadiabatic Dynamics of Atmospheric Molecules

ended

Our atmosphere appears to be a reservoir of inert gaseous molecules, while in reality, it is also composed of a plethora of highly reactive molecules and radicals. Among these are the volatile organic compounds (VOCs) that contribute substantially to both global warming and air pollution. Detailed atmospheric models attempt to describe the incredibly complex network of chemical reactions resulting from VOC oxidation in our troposphere and to predict its composition, paramount for informing societal and political decisions and regulations. A surprising observation, though, is that the role of sunlight in the reactions of VOC intermediates is scarcely understood, even though excited-state dynamics, triggered by sunlight absorption, initiate most of the atmosphere’s chemistry. This lack of information is partly due to the challenge in conducting photochemical experiments on transient VOC species. As a result, VOC-related chemical mechanisms are mostly based on a ground electronic state chemistry, leading to some critical deviations between the predicted and observed composition of the atmosphere. Also, vastly neglecting the rich photochemistry of these VOC species leads to a poorer understanding of their resulting environmental impact. This project, SINDAM, launches the field of in silico atmospheric photochemistry by using recent breakthroughs in theoretical and computational chemistry to establish the importance of photochemical processes of VOCs in the atmosphere, either in isolation or in contact with water molecules. SINDAM will answer the simple yet critical question: how ubiquitous are photophysical and photochemical effects in the atmospheric chemistry of VOCs? Hence, this project will stimulate an exciting new synergistic area at the edge between theoretical and atmospheric chemistry, leading to a real, societal impact by improving the predictive power of atmospheric models in the context of global warming and air quality.