This is a past event.

Barbara Finlayson-Pitts
University of California, Irvine

Richard Honrath Memorial Lecture

Oxides of nitrogen generated during fossil fuel combustion participate in a wide cycle of atmospheric reactions. This leads to the formation of a number of species including nitric acid and ozone, a toxic air pollutant for which air quality standards are set. A particularly important intermediate generated from NO2 is nitrous acid (HONO) which photolyzes to generate the OH radical, a major oxidant that drives atmospheric cycles. In studies over the continents in many locations around the world, including in the Arctic and Antarctic, HONO has been found to be the major OH source under many conditions, including in studies by Honrath and coworkers. Despite this key role of HONO, the mechanisms and kinetics of its formation remain obscure, although heterogeneous chemistry of NO2 on various surfaces that hold adsorbed water appears to be key. The current status of understanding of heterogeneous reactions of oxides of nitrogen will be presented in the context of laboratory and field studies, and remaining challenges highlighted.

Host: Will Cantrell