Gas phase detection and rotational spectroscopy of ethynethiol, HCCSH. (18th June 2019)

• Record Type: Journal Article
• Authors: Lee, Kin Long Kelvin; Martin-Drumel, Marie-Aline; Lattanzi, Valerio; McGuire, Brett A.; Caselli, Paola; McCarthy, Michael C.
• Is Part Of: Molecular physics. Volume 117:Number 9/12(2019)
• Page Start: 1381
• Page End: 1391
• Publication Date: 2019-06-18
• Subjects: Rotational spectroscopy -- astrochemistry -- molecular structure -- quantum chemistry; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2018.1552028
• Languages: English
• ISSNs: 0026-8976

Abstract

ABSTRACT: We report the gas-phase detection and spectroscopic characterisation of ethynethiol ( HCCSH ), a metastable isomer of thioketene ( H 2 C 2 S ) using a combination of Fourier-transform microwave and submillimetre-wave spectroscopies. Several a -type transitions of the normal species were initially detected below 40 GHz using a supersonic expansion-electrical discharge source, and subsequent measurement of higher-frequency, b -type lines using double resonance provided accurate predictions in the submillimetre region. With these, searches using a millimetre-wave absorption spectrometer equipped with a radio frequency discharge source were conducted in the range 280–660 GHz, ultimately yielding nearly 100 transitions up to r R 0 ( 36 ) and r Q 0 ( 68 ) . From the combined data set, all three rotational constants and centrifugal distortion terms up to the sextic order were determined to high accuracy, providing a reliable set of frequency predictions to the lower end of the THz band. Isotopic substitution has enabled both a determination of the molecular structure of HCCSH and, by inference, its formation pathway in our nozzle discharge source via the bimolecular radical-radical recombination reaction SH + C 2 H, which is calculated to be highly exothermic (−477 kJ/mol) using the HEAT345(Q) thermochemical scheme. GRAPHICAL ABSTRACT: