School of Chemistry

Research sheds new light on microscopic chemical physics driving atmospheric reaction sequences

31 August 2012

The results of a collaboration between Bristol's Dr David Glowacki and an international team including experimentalists and theoreticians based in Leeds, Cambridge (UK) and Chicago are published in Science. Their research sheds new light on the microscopic chemical physics driving one of the most important reaction sequences in atmospheric chemistry.

O₂ 'intercepting' an atmospheric pollutant radical - hot orange and cool blue colors show high and low energy quantum states, respectively

O₂ 'intercepting' an atmospheric pollutant radical - hot orange and cool blue colors show high and low energy quantum states, respectively

Within the Earth's atmosphere (and more generally) one of the most important classes of chemical reactions are so-called 'association reactions', where one molecule (A) reacts with another molecule (B). Contrary to the assumption that atmospheric association reactions always involve reactants in equilibrium states, Dr Glowacki and colleagues show that, for association reactions of the type O²+B there is a high probability that O² 'intercepts' B before its non-equilibrium quantum states have relaxed to equilibrium.

Their experimental and computational evidence shows that this occurs during the atmospheric degradation of acetylene, which is an important tracer of atmospheric pollution and also plays an important role in the formation of atmospheric particulates.

Furthermore, Dr Glowacki and colleagues show that the products produced when O² intercepts another molecule's non-equilibrium quantum states are different from those produced when states are in equilibrium.

http://www.sciencemag.org/content/337/6098/1066.abstract