# FOURIER-TRANSFORM MICROWAVE SPECTROSCOPY OF SULFUR-CONTAINING CARBON-CHAIN RADICALS

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 Title: FOURIER-TRANSFORM MICROWAVE SPECTROSCOPY OF SULFUR-CONTAINING CARBON-CHAIN RADICALS Creators: Hirahara, Yasuhiro; Ohshima, Yasuhiro; Endo, Yasuki Issue Date: 1993 Publisher: Ohio State University Abstract: Rotational spectra of sulfur-containing carbon-chain radicals, $C_{4}S(^{3}\Sigma^{-}), HC_{3}S(^{2}\Pi_{1/2})$, and $HC_{4}S(^{2}\Pi_{3/2})$, were observed for the first time by using a Fabry-Perot-type Fourier-transform microwave spectrometer combined with a pulsed discharge $nozzle.^{1}$ The species were generated in a supersonic free jet of a DC-discharged gas mixture of $C_{2}H_{2}$ and $CS_{2}$ diluted in Ar, which had been used for the first detection of the rotational spectrum of $C_{5}S(^{1}\Sigma^{+}).^{2}$ By semi-automatic frequency scans of 8--12 GHz, 14--15GHz and other regions, we detected the rotational spectra assignable to the new radicals in the ground electronic states. The spectrum of $HC_{3}S$ showed both the A-type doubling and the hyperfine splitting due to the H nucleus, whereas that of $HC_{4}S$ showed only the hyperfine splitting. The observed line frequencies of $C_{4}S, HC_{3}S$, and $HC_{4}S$ were fitted to the Hamiltonians appropriate to their electronic states, yielding effective molecular constants for the radicals. The present results enable us to search for these sulfur-containing carbon-chain radicals in interstellar media by using radiotelescopes. Description: $^{1}$ Y. Ohshima and Y. Endo, J. Mol. Spectrosc. 153, 627(1992). $^{2}$ Y. Kasai, K. Obi, Y. Ohshima, Y. Hirahara, Y. Endo, and K. Kawaguchi, Astrophys. J., submitted. Author Institution: Department of Pure and Applied Sciences, The University of Tokyo URI: http://hdl.handle.net/1811/18471 Other Identifiers: 1993-MG-10