Thermal stability of radiation-induced free radicals in gamma-irradiated L-alanine single crystals.
Decay of the radiation-induced stable free radicals in l-alanine single crystals and powders at the temperatures from 379 to 476 K was examined by electron paramagnetic resonance. For single crystals, the calculated activation energy of the radical decay is 104.3+/-1.7 kJ/mol (i.e. 12 538+/-202 K) and the frequency factor lnv (O) is 24.1+/-0.4 min(-1). The lifetime of the radical in single crystals at 296 K is 162 years. The results confirm the long-term stability of the radicals, but the decay was found to be faster in large crystals than in powders.
Maltar-Strmecki
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N
Faculty of Veterinary Medicine, University of Zagreb, P.O. Box 466, 10002 Zagreb, Croatia.
Rakvin
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B