Abstract The missing sulfur of the interstellar medium may be hiding in molecules for which there are no spectral data yet available for any astrophysical observation, molecules like isomers of H2CS a known interstellar compound. Every known interstellar molecule is a pointer to the presence and detectability of related molecules in the ISM. This quantum chemical study provides the necessary spectral data for the observation of cis-, trans-, and 3 A HCSH as well as for 1 A 1 and 3 A ″ H2SC. Benchmarks of the CCSD(T)-F12/cc-pVTZ-F12 quartic force field for the known thioformaldehyde provide anharmonic vibrational frequencies of with an average of 1.9 cm−1 of gas-phase experiment demonstrating reliability for the computed fundamental frequencies. The 1 A 1 H2SC form has bright spectral features in the infrared and millimeter-wave regimes, but is the highest-energy species of this set. The trans-HCSH isomer is the lowest-energy (43.69 kcal/mol or 1.90 eV) isomer next to thioformaldehyde, but the slightly higher cis-HCSH isomer has greater intensities for its brightest fundamental frequencies and a larger dipole moment making it potentially more likely to be observed. These data determined here may also assist in laboratory characterization of these molecules and how their chemistry will likely progress.

中文翻译：

---

已知星际分子硫代甲醛的顺式/反式-HCSH和H2SC异构体的理论旋转振动表征

摘要 星际介质中缺失的硫可能隐藏在尚无任何天体物理观测光谱数据的分子中，如已知星际化合物 H2CS 的异构体。每个已知的星际分子都是 ISM 中相关分子的存在和可检测性的指针。这项量子化学研究为观察顺式、反式和 3 A HCSH 以及 1 A 1 和 3 A″ H2SC 提供了必要的光谱数据。已知硫代甲醛的 CCSD(T)-F12/cc-pVTZ-F12 四次力场的基准提供平均为 1.9 cm-1 的气相实验的非谐振动频率，证明了计算基频的可靠性。1 A 1 H2SC 形式在红外和毫米波范围内具有明亮的光谱特征，但却是这组能量最高的物种。反式 HCSH 异构体是仅次于硫代甲醛的能量最低的异构体（43.69 kcal/mol 或 1.90 eV），但稍高的顺式 HCSH 异构体因其最亮的基频和更大的偶极矩而具有更大的强度，这使得它可能更有可能待观察。此处确定的这些数据也可能有助于对这些分子进行实验室表征以及它们的化学可能会如何发展。