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RADICAL AND TEMPERATURE DISTRIBUTIONS IN THE TRACKS OF FISSION RECOILS
Abstract
The yield of n-butane in the fission recoil induced radiolysis of gaseous ethylene in the presence of small quantities of oxygen is interpreted in terms of competition between radical combination in the track, radical diffusion, and radical removal by oxygen. The differential equations describing these reactions are solved and fitted to experiment by adjusting the initial mean track radius, r(,i), until calculations and observations agree. r(,i) is found to be substantially larger than the radius for physical energy deposition by primary interaction of the recoiling fission fragment or the radius within which secondary electrons (delta rays) deposit their energy. It is proposed that this is largely the result of diffusive spread of precursors to ethyl radical formation. These must survive for approximately 10('-9) seconds before competition for second order disappearance sets in. The observed dependence of r(,i) on the reciprocal square root of density is consistent with this postulate. The temperature of the fission recoil track is probed by utilizing the difference in the heats of formation of the isopropyl and normal propyl radicals (3.6 kcal/mole, 15.1 joule/mole). End products of the reactions of the isomeric propyl radicals are analyzed in the radiolysis of gaseous propane and a mixture of methane, ammonia and propane with gamma rays or fission recoils at the same density. The product distribution is independant of density in the gamma radiolysis while with fission recoil radiolysis the product distribution varies with density in a manner suggesting an increase in the temperature with density. The temperature measured or effective temperature of the medium is a time average of any initial increase in temperature until its decay to ambient. The effective temperature varies approximately linearly with density from ambient at 5 g/L to 40(DEGREES)C above ambient at 100 g/L. This is interpreted by invoking diffusive migration of the initial species in the physico-chemical stage for a finite relaxation interval. The dependence of the apparent effective temperature on the density of the medium is consistant with this model and gives a relaxation interval of 2 x 10('-10) seconds.
Subject Area
Chemistry
Recommended Citation
LAVERNE, JAY ALLEN, "RADICAL AND TEMPERATURE DISTRIBUTIONS IN THE TRACKS OF FISSION RECOILS" (1981). ETD collection for University of Nebraska-Lincoln. AAI8124516.
https://digitalcommons.unl.edu/dissertations/AAI8124516