Isotope effect in diffusion of methyl radicals in glassy ethanol-1,2d5 at low temperatures Original Research Article

The kinetics of methyl radicals decay has been studied at 77 K and at 90 K in glassy mixtures 0.9(xC2H5OH+(1−x)C2D5OH)+0.1H2O. It has been shown that in matrices with a small content of H-component (x≲0.02) the decay rate of CD3 radicals is noticeably higher than that of CH3. Upon H/D substitution in the methyl radical the rate of radical migration and the rate of deuterium atom abstraction from matrix molecules change simultaneously. As the fraction of C2H5OH in the mixture increases, the difference in the rates of the decay of methyl radical isotopomers vanishes. The unusual “inverse” isotope effect in the methyl radical diffusion is considered in the framework of the transition state theory.