| VIBRATIONAL AND ROTATIONAL LASER SPECTROSCOPY OF SUPERSONICALLY COOLED ALKOXY AND ALKYLTHIO $RADICALS^{*}$ (1994) | |||||||||
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| $^{*}$Financial support from the NASA Center for the Study of Terrestrial and Extraterrestrial Atmospheres (\# NASA NAGW-2950), U.S. Environmental Protection Agency's Office of Exploratory Research (\# R819720-01-0), and the Collaborative Core Unit of Howard University's Graduate School of Arts \& Sciences is gratefully acknowledged.. Author Institution: Laser Spectroscopy Laboratory, Department of Physics \& Astronomy, Howard University. The alkoxy $(RO R=CH_{3}, C_{2}H_{5}, i-C_{3}H_{2})$ and alkylthio (RS) free radicals are important chemical intermediates in gas-phase atmospheric and combustion chemistry. Laser-induced fluorescence (LIF), in conjunction with a supersonic jet environment, has been used to study the vibrational and rotational spectroscopy associated with electronic transitions involving these radicals. RO radicals were generated {in situ} in the supersonic expansion by excimer laser (KrF @ 248 nm) photolysis of RONO, while RS molecular fragments were produced form similar photodissociation of $R_{2}S_{2}$. Both Nd; YAG-pumped and excimer-pumped tunable dye laser systems were used to record rotationally-resolved laser excitation spectra of the jet-cooled RO and RS radicals. Wavelength-resolved emission spectra of $CH_{3}O$ and $CH_{3}S$ were obtained by exciting the molecules at the wavelength of strong rotational transition within a vibronic band. Several rotational and vibrational frequencies and parameters obtained from the assignments and leastsquares fits will be discussed in the context of the involved molecular spectroscopy of the RO and RS radicals. | |||||||||
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