Photochemical Reactions of Linear Alkane Radical Cations in Low-Temperature Matrices

The radical cations of linear alkanes (n-pentane, n-heptane) trapped in various matrices (Freon-11, Freon-113, Freon-113a, mixture of Freon-11 and Freon-114B2, and sulfur hexafluoride) were found to undergo the following types of photochemical reactions: (1) charge transfer to the matrix followed by neutralization, (2) isomerization and unimolecular decomposition, and (3) deprotonation. The absorption spectra of the radical cations were characterized, and the quantum yields of reactions occurring in different matrices at 77 K were determined. It was shown that the reaction pathway and efficiency of the photochemical processes observed for a given radical cation in different matrices with similar physical and chemical characteristics could considerably differ.