SEP SPECTROSCOPY OF THE HCCS RADICAL
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Date
2000
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
Stimulated Emission Pumping (SEP) spectroscopy has been applied to the study of the ground state vibronic structure of a linear tetra-atomic free radical, HCCS, which has two Renner-Teller active bending modes. The radical was produced in a supersonic jet by a pulsed discharge in a $C_{2}H_{2}$ and $CS_{2}$ mixture diluted in Ar. Two Nd YAG laser pumped dye lasers with linewidths $0.02 cm^{-1}$ are used to observe SEP spectra. Eight vibronic bands in the ground electronic states were observed from the $^{2} \Pi_{3/2}$ origin band excitation, and 4 bands from the $^{2}\Pi_{1/2}$ origin band excitation. Three of the observed bands are assigned to the CS stretching mode, and others to overtones and combinations of two bending modes with $\Pi$ vibronic symmetry. The observed vibronic energy levels are successfully analyzed by taking into accunt the Renner-Teller interaction including the cross vibronic terms. The determined parameters agree with previous ab initio $calculations^{a}$ and mm-wave $spectroscopy^{b}$.
Description
$^{a}$P. G. Szalay, J. Chem. Phys., 105, 2735 (1996), Y. Li and S. Iwata, Chem. Phys. Lett., 273, 91 (1997). $^{b}$J. Tang and S. Saito, J. Chem. Phys., 105, 8022 (1996).
Author Institution: Department of Basic Sciences, Graduate School of Arts and Sciences, University of Tokyo.
Author Institution: Department of Basic Sciences, Graduate School of Arts and Sciences, University of Tokyo.