Thermalization Distance Distribution in Liquid Hydrocarbons

we want to make a comment about possible local temperature rise due to energy absorption. An early theory of radiation effect s was based on the point-heat hypothesis (Dessauer, 1923). Later analysis showed that the temperature rise would be too feeble and too transient for low-LET radiation to cause any real change (see Mozumder, 1969). There is no experimental evidence for temperature rise for low-LET radiations. The case of high-LET radiations is still open, though. 

FIGURE 8.3 Geometric and energetic relationship for electron thermalization by random walk in liquid hexane in the presence of the geminate positive ion. Here = fid). Reproduced from Mozumder and Magee (1967), with the permission of Am. Inst. Phys. . 

Given (Ev, Rv) the probability density of thermalization around P may now be computed by the following sequence of steps (1) fix (r, 9) and compute Rj from Eq. (8.4) (2) evaluate N from Eq. (8.5) with assumed values of p and fid) then (3) obtain W from Eq. (8.6). Finally, a consistency check should be made so that r NL. Mozumder and Magee treated p as a parameter, taking ft = 0.01 eV 

In hydrocarbon liquids other than n-hexane, the procedure for obtaining the thermalization distance distribution could conceivably be the same. However, in practice, a detailed theoretical analysis is rarely done. Instead, the free-ion yield extrapolated to zero external field (see Chapter 9) is fitted to a one-parameter distribution function weighted with the Onsager escape probability, and the mean thermalization length (r ) is extracted therefrom (see Mozumder, 1974  

FIGURE 8.4 Electron thermalization distance distribution in n-hexane at 290K starting from an initial separation 23A. See text for details. Reproduced from Rassolov (1991). 

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