Temperature effect on recoil tritium reactions in solid alkanes at 20-300 K. Comparison of recoil tritium atoms with hydrogen(deuterium) atoms in radiolysis

Abstract

Hydrogen atom abstraction by recoil T atoms in neopentane and decane-d/sub 22/ has been studied at 20, 77, 195, and 300 K by means of ESR spectroscopy and radiogas chromatography. The results are compared with the reaction of H (or D) atoms produced by ..gamma.. radiolysis. When the experiments are conducted at 77 K, the reaction or recoil tritium atoms in the neo-C/sub 5/H/sub 12/-i-C/sub 4/H/sub 9/D (2 mol %) and n-C/sub 10/D/sub 22/-n-C/sub 10/H/sub 22/ (10 mol %) mixtures do not parallel those of H and D atoms generated by ..gamma.. irradiation, whereas the results at other temperatures below and above 77 K (20, 195, and 300 K) are more nealy comparable. The different results at 77 K are attributed to the ability of H and D atoms but not T atoms to diffuse and react with i-C/sub 4/H/sub 9/D (or n-C/sub 10/H/sub 22/) solute molecules. The failure of the thermal diffusion of the T atoms at 77 K is explained by a model in which nearly all of the recoil T atoms react either by hot reaction or have a high probability of reacting with a fragment near the end of the path and only a few percentmore » of them diffuse into the bulk matrix.« less