丙烷-1-硫醇（CH3CH2CH2SH）和丙烷-2-硫醇（(CH3)2CHSH）的转动光谱及天文搜寻

中文摘要 AI 辅助

本研究聚焦于丙硫醇（或丙基硫醇，C3H7SH），它是丙醇的含硫类似物，也是研究星际硫化学的关键目标。我们报道了其两种结构异构体——丙烷-1-硫醇（1PT）和丙烷-2-硫醇（2PT）——的实验室转动光谱表征。对于1PT，实验分析导致观察到三个几乎等能量的构象体，即Aa、Ag和Gg，其中后者为首次报道。对于2PT，anti和gauche两种构象体均被识别。我们还首次在自然丰度下指认了若干单取代同位素体：anti-2PT构象体的34S、13C1和13C2物种，以及gauche-2PT构象体的34S物种。由巯基（SH）基团的大振幅运动引起的隧穿分裂，在Ag-1PT和gauche-2PT两个构象体中均被观测到。整合先前测量的全局拟合，使得转动常数、四次离心畸变常数和振动耦合参数的精确确定成为可能。新推导的光谱参数被用于对化学丰富的银河系中心分子云G+0.693-0.027进行天文搜寻。虽然未发现丙硫醇的证据，但我们确立了其柱密度的严格上限。这些结果表明，在该源中，1PT和2PT的丰度分别约为乙硫醇的1/13和1/5。此外，对于1-丙醇/1-丙硫醇对，推导出的O/S比下限（29）与太阳值（37）一致，为理解星际介质中硫的耗损提供了宝贵的基准。

英文摘要

This study focuses on propanethiol (or propyl mercaptan, C3H7SH), a sulfur analogue of propanol and a key target for investigating interstellar sulfur chemistry. We report the laboratory rotational spectroscopic characterization of its two structural isomers, propane-1-thiol (1PT) and propane-2-thiol (2PT). For 1PT, experimental analysis led to the observation of three almost isoenergetic conformers, Aa,Ag and Gg, marking the first-time report of the latter. For 2PT, both the anti and gauche conformers were identified. We also assigned, for the first time, several monosubstituted isotopologues in natural abundance: the 34S, 13C1, and 13C2 species for the anti-2PT conformer, as well as the 34S species for the gauche-2PT conformer.Resolvable tunneling splitting, caused by the large-amplitude motion of the sulfhydryl (SH) group, was observed for both the Ag-1PT and gauche-2PT conformers. Global fittings, integrating previous measurements, allowed for the accurate determination of rotational constants, quartic centrifugal distortion constants, and vibrational coupling parameters. The newly derived spectroscopic parameters were utilized to conduct an astronomical search toward the chemically rich Galactic Center molecular cloud G+0.693-0.027. While no evidence for propanethiol was found, we established rigorous upper limits for their column densities. These results indicate that 1PT and 2PT are approximately 13 and 5 times less abundant than ethanethiol in this source, respectively. Furthermore, the derived lower limit for the O/S ratio (29) for the 1-propanol/1-propanethiol pair is consistent with the solar value (37), proviiding a valuable benchmark for understanding the depletion of sulfur in the ISM.

发表机构

• University of Bologna（博洛尼亚大学）
• Nanjing Institute of Atomic Scale Manufacturing（南京原子尺度制造研究所）
• Centro de Astrobiología (CAB), CSIC-INTA（天体生物学中心（CAB），西班牙国家研究委员会-国家航空航天技术研究所）

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