Gas phase detection and rotational spectroscopy of ethynethiol, HCCSH

摘要: We report the gas-phase detection and spectroscopic characterization of ethynethiol ($\mathrm{HCCSH}$), a metastable isomer thioketene ($\mathrm{H_2C_2S}$) using combination Fourier-transform microwave submillimeter-wave spectroscopies. Several $a$-type transitions normal species were initially detected below 40 GHz supersonic expansion-electrical discharge source, subsequent measurement higher-frequency, $b$-type lines double resonance provided accurate predictions in submillimeter region. With these, searches millimeter-wave absorption spectrometer equipped with radio frequency source conducted range 280 - 660 GHz, ultimately yielding nearly 100 up to $^rR_0(36)$ $^rQ_0(68)$. From combined data set, all three rotational constants centrifugal distortion terms sextic order determined high accuracy, providing reliable set lower end THz band. Isotopic substitution has enabled both determination molecular structure $\mathrm{HCCSH}$ and, by inference, its formation pathway our nozzle via bimolecular radical-radical recombination reaction $\mathrm{SH + C_2H}$, which is calculated be highly exothermic (-477 kJ/mol) HEAT345(Q) thermochemical scheme.