Radiation-Chemical Initiation of Chain Reactions

The rate Wgr of the radiation-chemical initiation of any chain reaction can be predicted with an accuracy of a factor of two assuming that 

For such a reaction at 300 K, radiative initiation becomes dominant over thermal initiation at J = 2.5 10 eV/cm s whereas at 600 K, it would require as much as J = 8 10 eV/ cm s. 

according to the Tal roze method, one has to find in the coordinates log J vs. 1/Tthe J and T ranges over which the following three criteria are satisfied  

It is easiest to obtain the needed region for unbranched chain reactions. This is illustrated by Fig. 65 describing the calculated dependences which satisfy the V- and w-criteria (curves 2 and 3). The region below curve 2 refers to chain lengths 

V 1 and that above curve 3 to condition (42.5). It follows from calculations (omitted here) that as the dose rate becomes higher, the contribution from second-order decay of active centers to the chain termination mechanism becomes increasingly important. This results in the deviation of curves 2 and 3 from the vertical asymptotes. 

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