Direct Studies of Peroxy Radical Autoxidation Reactions

Biogenic volatile organic compounds (BVOCs), emitted by plants, play a crucial role in climate by setting the background levels of aerosol in the atmosphere. Aerosols interact with solar radiation and have a cooling affect on climate. BVOCs also affect the NOx cycle and produce ozone. Ozone in the troposphere, lowest level of the atmosphere, is a potent greenhouse gas which warms the climate and also a major pollutant which negatively impacts air quality. Peroxy radicals are key intermediates involved in these physio-chemical processes and are formed with myriad of structural differences. These structures are predicted to have different chemical reactivities and thus varied potential to produce aerosols and ozone. However, until the recent breakthroughs in near infrared cavity ring-down spectroscopy understanding the distribution of peroxy radical structures and reactivity, and so the effects on aerosols and ozone, was impossible. Here we propose a combined laboratory and Earth system modelling project which will measure the key structure dependent physio-chemical properties of peroxy radicals from the most important BVOCs (isoprene and alpha-pinene), and integrate this knowledge to simulate the impacts of BVOCs on climate more faithfully than ever possible before.

The results from this project will be of direct benefit to academic researchers in atmospheric and physical sciences and policy makers planning for the environmental and climate changes in the near and long-term future. This project will help Dr Rabi Chhantyal Pun to start a new research program focused on laboratory photochemistry at the University of Nottingham, with modelling support from Prof Alexander Archibald at the University of Cambridge. It will also provide state of the art laboratory and atmospheric chemistry training for a new postdoctoral research associate.