Selective formation of solute radical by hydrogen atom in radiolysis and photolysis of alkane mixtures at 77 K

Selective formation of solute alkyl radicals in the radiolysis or photolysis of alkane mixtures has been studied by E.S.R. spectroscopy at 77 K. It is verified from several observations that the solute alkyl radicals are not formed by the energy transfer from the matrix to the solute alkane, but by the selective hydrogen atom abstraction reaction from the solutes by reactive H atoms which are produced by the radiolysis of solvent alkane or by the photolysis of hydrogen halides. The yields of the solute alkyl radical are measured as a function of solute concentration. It is shown that the occurrence of the selective hydrogen atom abstraction at 77 K cannot be explained by the previous theory of reaction kinetics in the gas phase, but that some new factors must be introduced for the explanation of the reaction in the solid phase at 77 K. (author)