Cage effect in the thermal decomposition of solid-state azobisisobutyronitrile

摘要

The method of cross-recombination of isotopically labeled NC(CH_3)_2C and NC(CD_3)_2C radicals with equal free-valence reactivity is applied to measure the cage effect, F = k_(rec)/(k_(rec) + k_(dif), in the thermal decomposition of azobis(isobutironitrile) in isomorphic crystals consisting by half of fully deuterated molecules of the initial substance. It is shown that the decomposition occurs at crystal lattice defects. The products are analyzed by chromatography-mass spectrometry at the degree of conversion of 1% at 70 C. The CE effect and diffusion coefficient at 70 C have been found to be F = 0.87 and D = 7.7 · 10~(-7) cm~2/s. These results are indicative of a high mobility of molecules on the inner surface of the crystal.