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Theoretical investigation of the interstellar CH/sub 3/NC/CH/sub 3/CN ratio

Journal Article · · Astrophys. J.; (United States)
DOI:https://doi.org/10.1086/163229· OSTI ID:5265803

Calculations have been performed to determine the abundance ratio of the metastable isomer CH/sub 3/NC to the stable isomer CH/sub 3/CN in dense interstellar clouds. According to gas phase, ion-molecule treatments, these molecules are both synthesized via protonated ion precursors. We have calculated the ratio of the formation rates of the protonated precursor ions: CH/sub 3/NCH/sup +/ and CH/sub 3/CNH/sup +/: synthesized via the radiative association reaction between CH/sup +//sub 3/ and HCN, which is thought to be the dominant formation process of the two isomeric ions. Our calculations, which involve both ab initio quantum chemistry and equilibrium determinations, lead to a predicted CH/sub 3/NCH/sup +//CH/sub 3/CNH/sup +/ formation rate ratio between 0.1 and 0.4. If this ratio is maintained in the neutral species formed from the precursor ions, theory predicts a sizable abundance for methyl isocyanide (CH/sub 3/NC) and lends credence to its tentative observation.

Research Organization:
Molecular Research Institute
OSTI ID:
5265803
Journal Information:
Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 293:1; ISSN ASJOA
Country of Publication:
United States
Language:
English