2025/01/27 by Hayley Bunn, Bunn, Hayley A., S. Spezzano +19
Chemistry · Earth and Planetary Sciences · #Astrophysics of Galaxies (astro-ph.GA) #Atmospheric Ozone and Climate #FOS: Physical sciences #Molecular Spectroscopy and Structure #Spectroscopy and Laser Applications
paper · pdf · doi:10.48550/arxiv.2501.15944
openalex publication_date 2025/01/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We report an extensive rotational spectroscopic analysis of singly deuterated methyl mercaptan (CH2DSH) using both millimeter and far-infrared synchrotron spectra to achieve a global torsional analysis of the three lowest torsional substates (e0, e1, and o1) of this non-rigid species. A fit including 3419 millimeter wave transitions along with 43 infrared torsional subband centers was performed with root mean square deviations of 0.233 MHz and 0.270 cm-1, respectively, resulting in 68 fit parameters. A spectroscopic catalogue built from this analysis for a temperature of 125 K has led to the first interstellar detection of CH2DSH towards the Solar-like protostar IRAS 16293-2422 B. We report the identification of 46 transitions, including eight relatively unblended lines, resulting in a derived column density of (3.0±0.3)×1014 cm-2. The column density ratio for HDCS/CH2DSH compared to HDCO/CH2DOH suggests a difference in the interstellar chemistry between the sulphur and oxygen complex organics, in particular a different link between H2CO and CH3OH and between H2CS and CH3SH. This is the first interstellar detection of a deuterated sulphur-bearing COM and therefore an important step into understanding the chemical origin of sulphur-based prebiotics.