PerspectiveChemistry

Vibrational Excitation Can Control Tropospheric Chemistry

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Science  31 Aug 2012:
Vol. 337, Issue 6098, pp. 1046-1047
DOI: 10.1126/science.1227528

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Summary

Earth's atmosphere is often compared to a low-temperature combustion system. Reactive hydrocarbons are emitted from both natural and anthropogenic sources and then oxidized by hydroxyl radicals (OH) through a complex chain of reactive free radicals. It is usually assumed that the molecules and radicals involved are all in their lowest energy states. However, on page 1066 of this issue, Glowacki et al. (1) show that a strikingly different product distribution can be obtained in the oxidation of acetylene depending on whether the radicals contain high amounts of internal (vibrational) energy or are fully relaxed. The study used a combination of experiment and theory to provide a complete description of the reaction of OH radicals with acetylene in the presence of varying amounts of O2 and N2.