Photodissociation yields for vibrationally excited states of sulfuric acid under atmospheric conditions

Abstract

Theoretical investigations of the dynamics of the sunlight initiated dehydration of sulfuric acid are performed under atmospheric conditions. The relevant time scales for collisional deactivation and for vibrational fluorescence, which may compete with sulfuric acid dehydration in the upper stratosphere and the mesosphere are evaluated to provide a realistic quantum yield consistent with spectroscopic and theoretical results. The results obtained allow evaluation of the J values for this photochemical reaction in the atmosphere. At the higher altitudes of the upper stratosphere and the mesosphere the J values obtained are sufficiently large to satisfy model requirements and explain field observations of SO2 vertical profiles and the concentration of condensation nuclei in the stratosphere for air of recent polar origin. Copyright 2007 by the American Geophysical Union.