THE PHOTODISSOCIATION DYNAMICS OF METHYL NITRATE
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Date
2006
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Publisher
Ohio State University
Abstract
Interest in the photodissociation mechanism of alkyl nitrates (RONO$_{2}$, where R = CH$_{3}$, C$_{2}$H$_{5}$, etc.) stems from recent experimental measurements in the troposphere indicating that they are an important component of ``missing NO$_{y}$''. In this study, the photodissociation dynamics of methyl nitrate, CH$_{3}$ONO$_{2}$, at 193 nm have been investigated by examining the products from the primary channel, namely, CH$_{3}$O and NO$_{2}$. Laser-induced fluorescence (LIF) spectroscopy was employed to probe the nascent internal energy distribution of the CH$_{3}$O radical, a small fraction of which was found to be produced with one quantum of C$\relbar$O stretch excitation. The stretch-excited methoxy was observed to be formed with a significantly greater degree of rotational excitation than the vibrational ground state. Furthermore, dispersed fluorescence measurements reveal that the NO$_{2}$ fragment is produced electronically excited with internal energies out to the NO + O dissociation limit, indicating that the initial excitation is strongly localized on the NO$_{2}$ moiety. Comparisons will be drawn with the analogous photodissociation of nitric acid, HONO$_{2}$.
Description
Author Institution: Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104; Department of Chemistry, Amherst College, Amherst, MA 01002