实验室光谱学、理论表征及对顺式-丙烯硫醛（CH2CHCHS）的天文搜索
Laboratory spectroscopy, theoretical characterization, and astronomical search for syn-propenethial (CH2CHCHS)
AI总结：
研究对丙烯硫醛高能异构体顺式-CH2CHCHS进行实验室表征及天文搜索，未检测到该异构体并得出柱密度上限。通过理论研究揭示其形成途径具异构体特异性，计算表明其易转化为低能异构体，强调电子结构和动力学效应在星际异构体丰度确定中的重要性。
AI中文摘要：
我们报告了丙烯硫醛高能异构体顺式-CH2CHCHS的实验室表征。在对TMC-1的QUIJOTE线调查中，星际介质中检测到了低能异构体反式-CH2CHCHS，但同一源中未检测到顺式异构体，得出其柱密度上限为1.5×10¹⁰ cm⁻²。理论研究表明CH2CHCHS最可能的形成途径具有高度异构体特异性，产生近95%的反式异构体。气相中隧穿介导的单分子异构化计算表明顺式-CH2CHCHS在约10³年的时间尺度上转化为低能反式异构体。我们得出结论，在寒冷和温暖的星际环境中检测顺式-CH2CHCHS都极具挑战性。这些结果强调了电子结构和动力学效应在确定不同星际环境中异构体丰度方面的重要性。
英文摘要：
We report the laboratory characterization of the higher-energy isomer of propenethial, syn-CH2CHCHS. While the lower-energy isomer, anti-CH2CHCHS, was detected in the interstellar medium during the QUIJOTE line survey of TMC-1, we report the non-detection of the syn isomer in the same source, deriving an upper limit to its column density of 1.5 $\times$ 10$^{10}$ cm$^{-2}$. A subsequent theoretical investigation into the origin of this non-detection reveals that the most plausible formation pathway for CH2CHCHS is highly isomer-specific, producing nearly 95\% of the anti isomer. This predicted branching ratio allows us to infer an even lower effective upper limit for the abundance of the syn isomer. In addition, calculations of tunneling-mediated unimolecular isomerization in the gas phase show that syn-CH2CHCHS converts to the lower-energy anti isomer on timescales of the order of 10$^{3}$ years. Overall, we conclude that the detection of syn-CH2CHCHS is highly challenging in both cold and warm interstellar environments. These results underscore the importance of electronic-structure and kinetic effects in determining isomer abundances across diverse interstellar environments.
