Jabri A, Tercero B, Margulès L, Motiyenko R A, Alekseev E A, Kleiner I, Cernicharo J, Guillemin J-C
Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est-Créteil, Université de Paris, Institut Pierre Simon Laplace (IPSL), 61 av. du Général de Gaulle, 94010 Créteil, France.
Observatorio Astronómico Nacional (OAN-IGN). Calle Alfonso XII, 3, 28014 Madrid, Spain.
Astron Astrophys. 2020 Dec 7;644:A102. doi: 10.1051/0004-6361/202038200. eCollection 2020 Dec.
S-methyl thioformate CHSC(O)H is a monosulfur derivative of methyl formate, a relatively abundant component of the interstellar medium (ISM). S-methyl thioformate being, thermodynamically, the most stable isomer, it can be reasonably proposed for detection in the ISM.
This work aims to experimentally study and theoretically analyze the ground and first torsional excited states for CHSC(O)H in a large spectral range for astrophysical use.
S-methyl thioformate was synthesized as a result of a reaction of methyl mercaptan with acetic-formic anhydride. The millimeter-wave spectrum was then recorded for the first time from 150 to 660 GHz with the solid-state spectrometer located at Lille.
A set of 3545 lines is determined and combined with 54 previously measured lines in the microwave region, belonging to ground state = 0 as well as 1391 transitions in the first excited state of torsion = 1. Some 164 lines were also assigned to = 2 for the A-species. A global fit was performed using the BELGI-C code taking into account the large splitting of A and E lines due to methyl internal rotation motion with a relatively low barrier, V = 127.4846(15) cm.
Using our spectroscopy work, a deep search of S-methyl thioformate was carried out in the IRAM 30m and ALMA data of different high-mass star-forming regions (Orion KL and Sgr B2). We derived an upper limit to the CHSC(O)H column density in these regions.
硫代甲酸甲酯CHSC(O)H是甲酸甲酯的单硫衍生物，而甲酸甲酯是星际介质（ISM）中相对丰富的成分。硫代甲酸甲酯在热力学上是最稳定的异构体，因此可以合理推测它能够在星际介质中被探测到。
这项工作旨在对硫代甲酸甲酯CHSC(O)H的基态和首个扭转激发态进行实验研究，并在较大光谱范围内进行理论分析，以供天体物理学使用。
硫代甲酸甲酯是由甲硫醇与乙酸 - 甲酸酐反应合成的。随后使用位于里尔的固态光谱仪首次记录了150至660GHz的毫米波光谱。
确定了一组3545条谱线，并将其与先前在微波区域测量的54条谱线相结合，这些谱线属于基态J = 0以及扭转第一激发态J = 1的1391个跃迁。还为A类物种的J = 2分配了约164条谱线。使用BELGI - C代码进行了全局拟合，考虑到由于甲基内旋转运动导致的A线和E线的大分裂，其势垒相对较低，V = 127.4846(15) cm⁻¹。
利用我们的光谱学工作，在不同高质量恒星形成区域（猎户座KL和人马座B2）的IRAM 30米望远镜和阿塔卡马大型毫米/亚毫米波阵列（ALMA）数据中对硫代甲酸甲酯进行了深入搜索。我们得出了这些区域中CHSC(O)H柱密度的上限。
