Accurate millimetre and submillimetre rest frequencies for $cis$- and $trans$-dithioformic acid, HCSSH

Abstract

A better understanding of sulphur chemistry is needed to solve the interstellar sulphur depletion problem. A way to achieve this goal is to study new S-bearing molecules in the laboratory, obtaining accurate rest frequencies for an astronomical search. We focus on dithioformic acid, HCSSH, which is the sulphur analogue of formic acid. The aim of this study is to provide an accurate line list of the two HCSSH $trans$ and $cis$ isomers in their electronic ground state and a comprehensive centrifugal distortion analysis with an extension of measurements in the millimetre and submillimetre range. We studied the two isomers in the laboratory using an absorption spectrometer employing the frequency-modulation technique. The molecules were produced directly within a free-space cell by glow discharge of a gas mixture. We measured lines belonging to the electronic ground state up to 478 GHz, with a total number of 204 and 139 new rotational transitions, respectively, for $trans$ and $cis$ isomers. The final dataset also includes lines in the centimetre range available from literature. The extension of the measurements in the mm and submm range lead to an accurate set of rotational and centrifugal distortion parameters. This allows us to predict frequencies with estimated uncertainties as low as 5 kHz at 1 mm wavelength. Hence, the new dataset provided by this study can be used for astronomical search.

References in corpus (8)

• Polycylcic Aromatic Hydrocarbons (PAH's) in dense cloud chemistry
• On the reservoir of sulphur in dark clouds : chemistry and elemental abundance reconciled
• Resetting chemical clocks of hot cores based on S-bearing molecules
• Sulfur depletion in dense clouds and circumstellar regions I. H2S ice abundance and UV-photochemical reactions in the H2O-matrix
• Spectroscopic characterization and detection of Ethyl Mercaptan in Orion
• A new study of an old sink of sulfur in hot molecular cores: the sulfur residue
• Accurate sub-millimetre rest-frequencies for HOCO${}^{+}$ and DOCO${}^{+}$ ions
• Polysulfanes on interstellar grains as a possible reservoir of interstellar sulphur

Cited by in corpus (6)

• Modeling Sulfur Depletion in Interstellar Clouds
• Anharmonic Vibrational Spectrum and Experimental Matrix Isolation Study of Thioformic Acid Conformers -- Potential Candidates for Molecular Cloud and Solar System Observations?
• Reexploring Molecular Complexity with ALMA: Insights into chemical differentiation from the molecular composition of hot cores in Sgr B2(N2)
• First Identification and Chemical Modeling of New Thiol ($-$SH) Bearing Molecule in the Interstellar Medium: Dithioformic Acid
• Rotational spectroscopic characterisation of the [D2,C,S] system: an update from the laboratory and theory
• Advancing spectroscopic understanding of HOCS${}^{+}$: Laboratory investigations and astronomical implications