Gamma radiolysis of polycrystalline djenkolic acid at room temperature produces two groups of carbon radicals. The radicals of group A either decay by a second-order reaction or are converted to sulfur radicals by a pseudo first-order process, while the radicals of group B can only be converted to sulfur radicals. The carbon radicals of groups A and B appear to be the same chemical species but differ in their microenvironments. Addition of${\rm Co}^{2+},\ {\rm Ni}^{2+}$, and Fe2+ at a ratio of 1 metal ion per 10 molecules of djenkolic acid decreases the initial yield of carbon radicals and increases the second-order decay rate and the percentage of carbon radicals belonging to group A. Addition of${\rm Na}_{2}{\rm SO}_{4},\ {\rm NaNO}_{3},{\rm CdSO}_{4}$, and${\rm Ni}^{2+}-{\rm EDTA}$ has no effect. The second-order decay may be explained by a vacancy-controlled bulk-diffusion process; metal ions appear to exert their influence by increasing the number of lattice defects. Addition of certain metals, particularly Cd2+ and${\rm Ce}^{4+}$ decreases the rate of conversion of the carbon radicals of group A to sulfur radicals. Ni2+ and${\rm Ce}^{4+}$ ions also prevent the radiation-induced destruction of sulfur radicals. The effects of metal ions on a variety of different processes can thus be differentiated in γ-irradiated djenkolic acid.

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