Pulse radiolytic investigation of cation kinetics in liquid and glassy alkane solutions

The formation and decay of solute cations in the pulse radiolysis of solutions of biphenyl, 1-methylstyrene, hexene-2, cyclohexene and limonen in glass-forming alkane matrices (methylcyclohexane, 3-methylheptane) have been investigated. Scavenger radical cations are generated by a fast and non diffusion-controlled electron-transfer reaction from solute molecules to holes which is complete within the electron pulse duration (10 ns) even at low temperatures in liquids as well as in glasses. In the alkenes the monomer radical cations dimerize by a diffusion-controlled reaction forming charge-resonance stabilized dimers which exhibit an optical absorption in the red region of the spectrum. This monomer-dimer behaviour has been especially characterized by temperature variation experiments. Some theoretical estimates to explain the observed fast electron-transfer reaction are given. (author)