The interstellar gas-phase chemistry of HCN and HNC

• DOI: 10.1093/mnras/stu1089
• Publication Date: 2014-07-11T00:03:10Z
• Authors: Jean-Christophe L...; Valentine Wakelam; Kevin M. Hickson
• Keywords: Hydrogen cyanide; Dissociative recombination; Branching fraction

We review the reactions involving hydrogen cyanide (HCN) and isocyanide (HNC) in dark molecular clouds to elucidate new chemical sources sinks of these isomers. find that most important for HCN–HNC system are dissociative recombination (DR) HCNH+ (HCNH+ + e−), ionic CN H3+, HCN C+, HNC with H+/He+/H3+/H3O+/HCO+, N CH2 reaction two reactions: H CCN C HNC. test effect rate constants branching ratios on predictions gas–grain models cloud conditions. The rapid keeps HCN/HNC ratio significantly above 1 as long carbon atom abundance remains high. However, H3+ followed by DR acts isomerize into when atoms CO depleted leading an close or slightly greater than 1. This agrees well observations TMC-1 L134N taking consideration overestimation abundances through use same rotational excitation many radiative transfer models.