YIELD OF THE O(P-3) ATOM IN THE RADIOLYSIS OF WATER BY 20-MEV H-2+ AND 40-MEV HE-42+

The production of O(3P) in the radiolysis of water with 2H+ and 4He2+ of initial energies 20 and 40 MeV, respectively, has been measured by determining the ethylene produced by the reaction of O(3P) with cyclopentene. The values obtained for G[O(3P)] are 4.7 X 10-3 and 4.5 x 10-3 for 2H+ and 4He2+, respectively, which can be compared with the γ-radiolysis value of 6.7 x 10-3. Consideration of the inhomogeneous kinetics of reactions in the tracks indicates that the initial G values for γ-radiolysis and 2H+ are nearly the same, but that the value for 4He2+ is significantly higher.