INVESTIGATION OF THIOKETENE ISOMERS: MICROWAVE SPECTROSCOPY AND FORMATION CHEMISTRY OF HCCSH

Because of their curious electronic properties, carbon-sulfide chains possess peculiar molecular structures and chemical reactivity. In this talk, we present the spectroscopic characterization of ethynethiol (\chem{HCCSH}) - an isomer of thioketene (\chem{H_2CCS}) and thiirene (c-\chem{H_2C_2S}) - and its isotopologues using Fourier-transform microwave cavity and millimeter-wave absorption spectroscopies. \chem{HCCSH} is produced in an electrical discharge of \chem{HCCH} and \chem{H_2S}. In our cavity spectrometer (10 - 40 GHz), the $J=1-0, 2-1, 3-2$ $a$-type transitions have been observed. \chem{HCC^{34}SH} was detected in natural abundance while the deuterated isotologues required \chem{HCCD} and \chem{D_2S} for \chem{DCCSH} and \chem{HCCSD} respectively. Based on \textit{ab initio} predictions, the fundamental $b$-type transitions were also measured using double resonance (150 - 300 GHz), allowing the $A$ constant to be determined approximately and guiding subsequent surveys into the millimeter-wave (280 - 655 GHz). Based on the information derived from the isotopologues, we will also discuss the molecular structure and inferred formation chemistry, in addition to its relative abundance to thioketene