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Gas phase chemistry of pyrene and related cations with molecules and atoms of interstellar interest

1999; Elsevier BV; Volume: 185-187; Linguagem: Inglês

10.1016/s1387-3806(98)14217-3

1873-2798

Valéry Le Page, Yeghis Keheyan, Theodore P. Snow, Veronica M. Bierbaum,

Photochemistry and Electron Transfer Studies

The chemistry of the pyrene radical cation C16H10+ and its derivatives C16H9+ and C16H11+ has been investigated in the gas phase using a flowing afterglow-selected ion flow tube. Rate coefficients have been determined for reactions between C16Hn+ (n = 9, 10, 11) and H2, CO, H2O, and NH3 molecules as well as H, O, and N atoms. These studies supplement previous investigations on the smaller benzene and naphthalene cations. It is found that C16H10+ and C16H11+ display consistent, predictable chemistry with reactivities very similar to those of benzene and naphthalene cations. On the other hand, the striking reactivity of C16H9+ toward atoms, compared to the relative unreactivity of phenylium and naphthylium cations, is believed to result from the triplet nature of this ion in its ground state. Ab initio calculations have been carried out to validate this hypothesis in conjunction with experimental evidence.