Submillimeter spectroscopy and astronomical searches of vinyl mercaptan, C${}_2$H${}_3$SH

Abstract

We have extended the pure rotational investigation of the two isomers syn and anti vinyl mercaptan to the millimeter domain using a frequency-multiplication spectrometer. The species were produced by a radiofrequency discharge in 1,2-ethanedithiol. Additional transitions have been re-measured in the centimeter band using Fourier-transform microwave spectroscopy to better determine rest frequencies of transitions with low-$J$ and low-$K_a$ values. Experimental investigations were supported by quantum chemical calculations on the energetics of both the [C${}_2$,H${}_4$,S] and [C${}_2$,H${}_4$,O] isomeric families. Interstellar searches for both syn and anti vinyl mercaptan as well as vinyl alcohol were performed in the EMoCA (Exploring Molecular Complexity with ALMA) spectral line survey carried out toward Sagittarius (Sgr) B2(N2) with the Atacama Large Millimeter/submillimeter Array (ALMA). Highly accurate experimental frequencies (to better than 100 kHz accuracy) for both syn and anti isomers of vinyl mercaptan have been measured up to 250 GHz; these deviate considerably from predictions based on extrapolation of previous microwave measurements. Reliable frequency predictions of the astronomically most interesting millimeter-wave lines for these two species can now be derived from the best-fit spectroscopic constants. From the energetic investigations, the four lowest singlet isomers of the [C${}_2$,H${}_4$,S] family are calculated to be nearly isoenergetic, which makes this family a fairly unique test bed for assessing possible reaction pathways. Upper limits for the column density of syn and anti vinyl mercaptan are derived toward the extremely molecule-rich star-forming region Sgr B2(N2) enabling comparison with selected complex organic molecules.

arXiv comment13 pages, 5 figures, 2 tables, 2 appendices. Accepted for publication in A&A 13th of February, 2019

References in corpus (14)

• The Cologne Database for Molecular Spectroscopy, CDMS, in the Virtual Atomic and Molecular Data Centre, VAMDC
• Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)
• Exploring Molecular Complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)
• Resetting chemical clocks of hot cores based on S-bearing molecules
• Weeds: a CLASS extension for the analysis of millimeter and sub-millimeter spectral surveys
• Sulfur depletion in dense clouds and circumstellar regions I. H2S ice abundance and UV-photochemical reactions in the H2O-matrix
• Exploring molecular complexity with ALMA (EMoCA): Alkanethiols and alkanols in Sagittarius B2(N2)
• Spectroscopic characterization and detection of Ethyl Mercaptan in Orion
• Sulphur-bearing molecules in diffuse molecular clouds: new results from SOFIA/GREAT and the IRAM 30 m telescope
• Submillimeter absorption from SH+, a new widespread interstellar radical, 13CH+ and HCl
• Discovery of interstellar mercapto radicals (SH) with the GREAT instrument on SOFIA
• Laboratory and tentative interstellar detection of trans-methyl formate using the publicly available Green Bank Telescope PRIMOS survey
• Investigating the Minimum Energy Principle in Searches for New Molecular Species - the Case of H${}_2$C${}_3$O Isomers
• The sulfur depletion problem: upper limits on the H2S2, HS2, and S2 gas-phase abundances toward the low-mass warm core IRAS16293-2422

Cited by in corpus (6)

• Astrochemistry During the Formation of Stars
• Precursors of fatty alcohols in the ISM: Discovery of n-propanol
• Sulfur Ice Astrochemistry: A Review of Laboratory Studies
• Diastereoselective Formation of trans-HC(O)SH Through Hydrogenation of OCS on Interstellar Dust Grains
• Formation of S-bearing complex organic molecules in interstellar clouds via ice reactions with C2H2, HS, and atomic H
• Reexploring Molecular Complexity with ALMA: Insights into chemical differentiation from the molecular composition of hot cores in Sgr B2(N2)