Radiation chemistry of overirradiated aqueous solutions of hydrogen cyanide and ammonium cyanide

Aqueous solutions (O2-free) of HCN and NH4CN were subjected to high doses (of up to 230 Mrad) of Co-60 gamma radiation, and the products were analyzed by chromatographic and chemical methods. The findings suggest the presence of two main stages of radiolysis. The first stage involves absorbed doses below 50 Mrad. At doses up to 20 Mrad, decomposition of cyanide is accompanied by formation of high-MWt products of 2000-20,000 daltons and of aminoacids (aa). The concentrations of these products decrease at doses of 20-50 Mrad, with increased accumulation of H2, NH3, CO2, CH4, CO, amides, and carboxylic acids. In the second stage, at doses of 50-230 Mrad, the concentrations of NH3, CO2, and amides remain stable, but the abundance of 6000-20,000 dalton polymers decreases, with the concomitant increase of 2000-6000 dalton oligomers. Carboxylic acids and aa are found at all doses of radiation. The relevance of these findings to phenomena on the primitive earth and within a cometary nucleus is discussed.