Laboratory rotational spectrum and astronomical search of s-methyl thioformate

Methyl thioformate CH$_{3}$SC(O)H, is a monosulfur derivative of methyl formate, a relatively abundant component of the interstellar medium (ISM)\footnote{E. Chruchwell, G. Winnewisser, A\&A, 45, 229 (1975)}. Methyl thioformate being the thermodynamically most stable isomer with a C$_{2}$H$_{4}$OS formula, it can be reasonably proposed for detection in the ISM. Theoretical investigations on this molecule have been done recently by Senent et al.\footnote{M. L. Senent, C. Puzzarini, M. Hochlaf, R. Domínguez-Gómez and M. Carvajal, J. Chem. Phys., 141, 104303 (2014)}. Previous experimental studies on this molecule have been performed by Jones et al.\footnote{G. I. L. Jones, D. G. Lister and N. L. Owen, J. Mol. Spectrosc., 60, 348 (1976)} and Caminati et al.\footnote{W. Caminati, B. P. V. Eijck and D. G. Lister, J. Mol. Spectrosc., 90, 15 (1981)} and its microwave spectrum was recorded between 10 and 41 GHz.\\ In this study, S-methyl thioformate has been synthesized by reaction of methyl mercaptan with formic-acetic anhydride. The millimeter wave spectrum was then recorded for the first time from 150 to 660 GHz with the Lille’s spectrometer based on solid-state sources \footnote{O. Zakharenko, R. A. Motiyenko, L. Margul\`es, T. R. Huet., J. Mol. Spectrosc., 317, 41 (2015)}. Around 2300 lines were assigned up to $J = 70$ and $K = 15$ and a fit for the ground torsional state $\nu_{t}=0$ performed with the \textit{BELGI-C$_{s}$} code\footnote{J. T. Hougen, I. Kleiner, and M. Godefroid, J. Mol. Spectrosc. 163, 559 (1994)} will be presented and discussed. Our aim is to provide a line list for an astrophysical research