15min:

M. E. SANZ, M. C. MCCARTHY, Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 and Division of Engineering and Applied Sciences, Harvard University, 29 Oxford St., Cambridge, MA 02138, USA; P. BOTSCHWINA, Institut für Physikalische Chemie, Universität Göttingen, Tammannstr. 6, D-37077 Göttingen, Germany; AND P. THADDEUS, Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 and Division of Engineering and Applied Sciences, Harvard University, 29 Oxford St., Cambridge, MA 02138,USA.

The linear singlet chains SiC₂S, SiC₄S and SiC₆S, as well as the triplet SiC₃S, have been detected among the products of a laboratory discharge on the basis of high level coupled cluster ab-initio calculations and characterized by Fourier transform microwave spectroscopy. The molecules were generated in a supersonic expansion of diluted mixtures of silane, diacetylene and carbon disulfide in Ne. Their rotational and centrifugal distortion constants were accurately determined, as was the spin-spin coupling constant for triplet SiC₃S. The microwave spectra of the ²⁹Si, ³⁴S and both ¹³C isotopic species of SiC₂S were measured, allowing a determination of the individual bond lengths. In addition, several satellite lines were observed near the rotational transitions of SiC₂S, which were identified as belonging to different bending and stretching vibrational excited states.