Marcin Gronowski

Computational Chemistry


A Theoretical Study on the Interstellar Synthesis of H2NCS+ and HNCSH+ Cations

HNCS and NCSH molecules, recently discovered in the interstellar medium, are likely formed via the dissociative recombination of H2NCS+ or HNCSH+ isomeric ions. Interstellar synthesis of the latter is discussed on theoretical grounds. The analysis of relevant potential energy surfaces suggests a key role for chemical processes in which CSH+ or HCS+ cations (most likely formed in CS + H3+ collisions) react with NH2 or NH3. The astrochemical kinetic database (kida.uva.2011), appended with 7 sulfur-bearing molecules and 48 corresponding reactions, has been applied to model the evolution of HNCS, NCSH, and their cationic precursors in a quiescent molecular cloud. Based on the model and on spectroscopic predictions, for an object like TMC-1, we expect the total intensity of H2NCS+ microwave lines to be comparable to that observed for HSCN. Theoretically derived molecular parameters, of interest for radio spectroscopy, are given for the most stable cations sharing the H2NCS+ stoichiometry.

Full text:  ApJ 792 89 doi:10.1088/0004-637X/792/2/89

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