文章基本信息

标题：Hyperfine excitation of SH + by H
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作者：François Lique ; Alexandre Zanchet ; Niyazi Bulut 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2020
卷号：638
页码：1-5
DOI：10.1051/0004-6361/202038041
语种：English
出版社：EDP Sciences
摘要：Context.SH+is a surprisingly widespread molecular ion in diffuse interstellar clouds. There, it plays an important role by triggering the sulfur chemistry. In addition, SH+emission lines have been detected at the UV-illuminated edges of dense molecular clouds, so-called photo-dissociation regions (PDRs), and toward high-mass protostars. An accurate determination of the SH+abundance and of the physical conditions prevailing in these energetic environments relies on knowing the rate coefficients of inelastic collisions between SH+molecules and hydrogen atoms, hydrogen molecules, and electrons.Aims.We derive SH+–H fine and hyperfine-resolved rate coefficients from recent quantum calculations for the SH+–H collisions, including inelastic, exchange, and reactive processes.Methods.The method we used is based on the infinite-order sudden approach.Results.State-to-state rate coefficients between the first 31 fine levels and 61 hyperfine levels of SH+were obtained for temperatures ranging from 10 to 1000 K. Fine-structure resolved rate coefficients present a strong propensity rule in favor of Δj = ΔNtransitions. The Δj = ΔFpropensity rule is observed for the hyperfine transitions.Conclusions.The new rate coefficients will help significantly in the interpretation of SH+spectra from PDRs and UV-irradiated shocks where the abundance of hydrogen atoms with respect to hydrogen molecules can be significant.
关键词：enmolecular datamolecular processesradiative transfermethods: laboratory: molecular