# INTERNAL ENERGY DISTRIBUTION OF CH$_{3}$O (X$^{2}E$) FROM PHOTODISSOCIATION OF METHYL NITRATE

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 Title: INTERNAL ENERGY DISTRIBUTION OF CH$_{3}$O (X$^{2}E$) FROM PHOTODISSOCIATION OF METHYL NITRATE Creators: Derro, Erika L.; Murray, Craig; Lester, Marsha I.; Marshall, Mark D. Issue Date: 2006 Publisher: Ohio State University Abstract: The methoxy (CH$_{3}$O) radical has attracted a great deal of attention in the literature due to its unique spectroscopy, as well as its importance as a reactive intermediate in combustion and atmospheric chemistry. In this study, we employ CH$_{3}$O as a dynamical probe of the photodissociation dynamics of methyl nitrate, CH$_{3}$ONO$_{2}$, at 193 nm. Rotationally-resolved spectra of the CH$_3$O photoproduct were recorded in the $A^{2}A_{1}\relbar X^{2}E$ system under both nascent and jet-cooled conditions using laser-induced fluorescence (LIF) spectroscopy. CH$_{3}$O $A^{2}A_{1}\relbar X^{2}E$ transitions could be simulated effectively using known spectroscopic constants at the lowest temperatures achieved under jet-cooled conditions. Spectra recorded at warmer temperatures are being used to refine reported spectroscopic constants. Under nascent conditions, transitions were observed from the vibrationless level of CH$_{3}$O ($X^{2}E$) as well as with C$\relbar$O stretch vibrational excitation, and the vibrational branching ratio is determined. The rotational excitation of these vibrational bands was fit to a Boltzmann distribution to extract nascent rotational temperatures. The experimental data indicate that the CH$_{3}$O fragment is produced with minimal internal energy (1\% of the available energy) following photodissociation of CH$_{3}$ONO$_{2}$ at 193 nm. Description: Author Institution: Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104; Department of Chemistry, Amherst College, Amherst, MA 01002 URI: http://hdl.handle.net/1811/31054 Other Identifiers: 2006-RJ-12