DETERMINATION OF SEVERAL NEW VIBRATIONAL FREQUENCIES FOR THE ETHOXY RADICAL
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Date
1995
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
The ethoxy molecule is an important chemical intermediate in combustion and atmospheric processes. It was formed by excimer laser-induced photolysis of ethylnitrite in a pulsed supersonic expansion. A frequency-doubled Nd:YAG-pumped dye laser in the UV with a nominal linewidth of $0.07 cm^{-1}$ served as the probe beam for recording rotationally-resolved excitation spectra of the B-X system in the $310-344$ nm region. Wavelength calibration was carried out using optogalvanic transitions employing an iron-neon lamp. In addition to the strong CO-stretch progression, several distinct excited state frequencies have been identified, namely: ${\nu_{4}}^{\prime}(CH_{2} scis)=1460 cm^{-1}, {\nu_{7}}^{\prime}(CH_{2} wag)=1323 cm^{-1}, {\nu_{9}}^{\prime}(CC stretch)=869 cm^{-1}, {\nu_{10}}^{\prime}(CO strech)=603 cm^{-1}, {\nu_{11}}^{\prime}(CCO deform)=362 cm^{-1}, {\nu_{17}}^{\prime}(CH_{2} rock)=893 cm^{-1}$ and ${\nu_{18}}^{\prime}(Torsion)=244 cm^{-1}$. Single vibronic level dispersed fluorescence spectra were recorded by exciting the molecules at the wavelength of a rotational transition within a vibronic band. Such dispersed spectra were obtained with an optical multichannel analyzer system used in conjunction with a cooled CCD detector. Besides the main CO-stretch progression in the wavelength-resolved emission spectra, there were other distinct ground state frequencies that could be identified and assigned: $\{nu_{2}}^{\prime\prime}(CH_{2} s-stretch)=2753 cm^{-1}, {\nu_{9}}^{\prime\prime} (CC stretch)=910 cm^{-1}, {\nu_{10}}^{\prime\prime} (CO stretch)= 1068 cm^{-1}, {\nu_{11}}^{\prime\prime} (CCO deform)=444 cm^{-1}, {\nu_{15}}^{\prime\prime}(CH_{2} twist)=1277 cm^{-1}, {\nu_{16}}^{\prime\prime}(CH_{3} rock)=984 cm^{-1}, {\nu_{17}}^{\prime\prime}(CH_{2} rock)=943 cm^{-1}$ and ${\nu_{18}}^{\prime\prime}(torsion)=370 cm^{-1}$.
Description
$^{\ast}$Financial support from the U.S. Environmental Protection Agency's Office of Exploratory Research (# R819720-01-0), NASA Lewis Research Center (# NAG3-1677) and the Center for the Study of Terrestrial and Extraterrestrial Atmospheres (# NASA NAGW-2950) is gratefully acknowledged.
Author Institution: Howard University, Washington, D.C. 20059.
Author Institution: Howard University, Washington, D.C. 20059.