Energy transfer in radiolysis of rare gas-perfluoroethane liquid

ENERGY TRANSFER I N RADIOLYSIS OF RAREGAS-C~FB LIQUIDa

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Energy Transfer in Radiolysis of Rare Gas-C,F, Liquid Mixtures by Alicja Sokolowska and Larry Kevan Department of Chemistry, University of Kansas, Lawrence, Kansas

66044 (Received July 18, 1967)

The liquid-phase y radiolysis of C2F6 with Xe, Kr, and Ar has been investigated as a function of the fraction of energy deposition in the rare gas in the presence and absence of O2 as a radical scavenger. All energy-transfer efficiencies are smaller by a factor of 2-3 than those found previously in the gas phase. The energy-transfer efficiencies in the absence of O2are similar for Xe and Ar, and twice as great for Kr. It is suggested that this reflects the correspondence between ionic states of Krz+ and C2F6+, and that charge transfer contributes to the energy-transfer process. In the presence of 02,no energy-transfer contribution to nonscavengeable products is observed; this implies that excitation transfer processes are inefficient or are quenched by 02.

Introduction Energy transfer in radiolysis of rare gaS-CzF6 mixtures has been previously studied in the gas phase.' It was shown that the over-all energy-transfer efficiency depended on the difference between the recombination energies of C2F6 and a given rare gas, and it was suggested that charge-transfer processes would show such behavior. C2Feis suitable for such studies since its recombination energy (14-16 ev) lies within the range of recombination energies (12-24 ev) spanned by the rare gases. Recent mass spectrometric studies on charge-transfer cross sections of rare gas ions with C2F6 confirm that the cross sections are largest when the recombination energy difference is srnalL2 I n this paper, we extend the macroscopic radiolysis approach for studying eneirgy transfer t o the liquid phase. The liquid phase radiolysis of C2F6 has been previously studied3 to provide a suitable background. C2F6 radiolysis in liquid Xe, Kr, and Ar is reported here. The effect of phase on total energy-transfer efficiency and evidence for the role of charge transfer in the liquid phase are discussed. Experimental Section C2F6 (Air Products Inc.) quoted as 99.9% pure contained