文章基本信息

标题：Formation of interstellar SH + from vibrationally excited H 2: Quantum study of S + + H 2 ⇄ SH + + H reaction and inelastic collision
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作者：Alexandre Zanchet ; François Lique ; Octavio Roncero 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2019
卷号：626
DOI：10.1051/0004-6361/201935471
语种：English
出版社：EDP Sciences
摘要：The rate constants for the formation, destruction, and collisional excitation of SH+are calculated from quantum mechanical approaches using two new SH+2potential energy surfaces (PESs) of4A″ and2A″ electronic symmetry. The PESs were developed to describe all adiabatic states correlating to the SH+(3Σ−) + H(2S) channel. The formation of SH+through the S++ H2reaction is endothermic by ≈9860 K, and requires at least two vibrational quanta on the H2molecule to yield significant reactivity. Quasi-classical calculations of the total formation rate constant for H2(v = 2) are in very good agreement with the quantum results above 100 K. Further quasi-classical calculations are then performed forv = 3, 4, and 5 to cover all vibrationally excited H2levels significantly populated in dense photodissociation regions (PDR). The new calculated formation and destruction rate constants are two to six times larger than the previous ones and have been introduced in the Meudon PDR code to simulate the physical and illuminating conditions in the Orion bar prototypical PDR. New astrochemical models based on the new molecular data produce four times larger SH+column densities, in agreement with those inferred from recent ALMA observations of the Orion bar.
关键词：enmolecular processesphoton-dominated region (PDR)ISM: molecules