Radical Formation in X-Irradiated Glycine HCl

Electron spin resonance spectroscopy was used to identify the electron and hole traps in single crystals of glycine HCl x irradiated at 4.2°K. Holes are trapped by the formation of Cl₂⁻ ions and electrons by the formation of $$\begin{array}{ccccccc}& & & & & & {\mathrm{O}}^{-}\\ & & & & & /& \\ {\mathrm{Cl}}^{-}({\mathrm{NH}}_3{)}^{+}& —& {\mathrm{CH}}_2& —& \mathrm{C}& & \\ & & & & & \backslash & \\ & & & & & & \mathrm{OH}\end{array}$$ Upon warming, the neutral radical CH₂–COOH is formed, which is identical with the radical produced in irradiated crystals of the free amino acid. The advantage of using the hydrochloride salt in this investigation is that the Cl₂⁻ ions are very stable and it is possible to observe unequivocally that the neutral radical is formed concomitantly with the decay of the glycine HCl negative ion.