PHOTOSENSITIVITY OF PARAMAGNETIC CENTERS IN RADIOLYZED SOLID HYDROGEN-CYANIDE

The photolysis of solid hydrogen cyanide and the effects of UV light o n Co-60-gamma-irradiated HCN at 77 K were studied using an ESR techniq ue. As in the case of radiolysis, the H2C=N-. radical formed due to '' sticking'' of the H atom to the triple bond of the HCN molecule is the main radical product of low-temperature HCN photolysis. The C=N-. rad icals are accumulated at 77 K in insignificant amounts (similar to 3 % ). It was established that radical and ionic products stabilized in ga mma-irradiated HCN possess photochromism and under the action of UV li ght enter photochemical reactions leading to their decomposition. Upon photobleaching, the concentration of H2C=N-. radicals first increases two- to threefold because of the decomposition of H2C=N- ions and the n decreases. The presence of radicals and ions formed upon the low-tem perature radiolysis of HCN broadens the optical absorption band of the system, and the boundary of the action spectrum shifts from 280 nm (f or nonirradiated HCN) to the visible region at 400-440 nm.