VIBRONIC AND ROTATIONAL STRUCTURE OF THE ASYMMETRIC C-H STRETCH OF METHOXY AND $d_{2}$-METHOXY RADICALS.

Abstract

Multimode Jahn-Teller analysis of the e modes in the $\tilde{X}$ state of the $CH_{3}O$ radical has been initiated using the SOCJT $program^{a}$ with special attention being paid to the asymmetric C-H stretch mode $(n_{4})$ for which there are several relevant experimental observations. Dispersed Fluorescence (DF) spectra have been recorded via excitation of $\tilde{A}^{2}A_{1} 3^{n}4^{1} (n = 1,2,3)$ combination levels for $CH_{3}O$. DF spectra have also been obtained upon $3^{n}(4^{\prime})^{1}(n = 1,2)$ LIF excitation for the $CHD_{2}O$ isotopomer. For both isotopomers the observed spectra reveal the quartet vibronic structure in the C-H stretch mode region. The observed quartet structure exhibits a large $({\sim}130 cm^{-1}$ for $CH_{3}O$ and ${\sim}160 cm^{-1}$ for $CHD_{2}O)$ separation; each component is further split into doublets (${\sim}25 cm^{-1}$ and ${\sim}35 cm^{-1}$ respectively for $CH_{3}O$ and $CHD_{2}O$). In addition, the rotationally resolved structure of the $\nu_{4}$ C-H stretch band of $CH_{3}O$, recorded via stimulated emission pumping technique was compared with that recently obtained from IR $spectra^{b}$. The implications of the rovibronic structure for the vibronic assignments will be discussed.