TRITIcnf
3115
6-RADIATIOS-INDUCED ISOTOPIC EXCHANGE WITH WATER VAPOR
excitation been locat,ed farther from the perchlorate excitation. The higher chloride yield may also arise
from secondary reactions with free radicals suffered by C103- as it diffuses out of the track.
Tritium p-Radiation-Induced Isotopic Exchange with Water Vapor
by John Y. Yang and L. H. Gevantman U . S . Naval Eadiological Defense Laboratory, S a n Francisco, California
(Received February 24, 1964)
The rate of tritium 6-decay-induced isotopic exchange between tritium gas and water vapor is found to be constant within a fourfold variation in the water vapor density, but to increase as a second-order function of the tritium concentration. Inert gases, present in large excess, appeared to function purely as moderating media for the tritium 6-energy. With helium gas as the moderator and tritium concentration in the range from 0.05 to 0.7 c./l., the reaction rate in mc./l.’/day at the ambient temperature of 22 =t2’ is observed as d(HTO)/dt = 3.6 X 10-5(T2)2,where (Tz) is the initial tritium concentration in mc./l. This exchange reaction is strongly inhibited by the presence of nitric oxide in the reaction mixture. The results are consistent with a reaction mechanism involving radical intermediates.
Introduction Ever since the dmcoveryl of tritium incorporation in organic compounds by exposure to tritium gas, a number of investigations devoted to detailed studies of the isotopic exchange in tritium-hydrocarbon systems have appeared in the literature.2-10 Although the over-all reaction mechanism appears to vary consid&ably with each individual system, it is generally agreed that the tritium /3-radiation-induced intermediates play a major ‘Or tritium in the Organic substrate. We Chose to stud:y the tritium-water vapor system because radiolytic processes in aqueous systems are reasonably well un
