Phase Effects in the Radiation Chemistry of Organic Compounds which may arise from Long-Range Energy Transfer

Abstract

WE have recently investigated the γ-ray-induced destruction of the solute (S = either I₂, FeCl₃ or DPPH) in dilute liquid and solid solutions in the organic solvents listed here. For all liquid solutions at 30° C. G (−S) is independent of solute concentration and dose and shows the expected dependence on solvent structure (Table 1). In contrast to this simple situation the corresponding solid solutions show the following two distinct types of radiation response: (1) Crystalline solutions in diethyl ether or dioxan and glassy solutions in phenetole or 2-methyl tetra-hydrofuran have G(−FeCl₃) values which are independent of dose, temperature and solute concentration and are smaller than the values for the corresponding liquid solutions. (2)G(−S) for crystalline solutions of FeCl₃ in the first four solvents in Table 1 and of iodine in diphenyl ether or phenetole² is markedly dependent on concentration, increases with diminishing temperature of irradiation and may be very much larger than the value in the liquid phase. This behaviour is illustrated in Fig. 1.