SPECTRA AND PHOTOLYSIS OF PURE NITROGEN AND METHANE DISPERSED IN SOLID NITROGEN WITH VACUUM-ULTRAVIOLET LIGHT

Abstract

Vacuum–ultraviolet light from a synchrotron was applied to record absorption spectra in the region of 105–170 nm with a resolution of 0.2 nm and for the photolysis of pure solid N2 and CH4 dispersed in solid N2 (CH4/N2 = 1/100 for absorption and 1/500 for photolysis) at 20 K. After photolysis of the icy samples at wavelengths 130 nm (9.5 eV), 121.6 nm (10.2 eV), and 91.6 nm (13.5 eV), infrared absorption features of products N3, CnN (n = 1–3), CN2, (CN)2, HCN2, HC2N, C(NH)2, HN3, HNC, HCN, HCCNH+, and NCCN+ were identified. We investigated the dependence on wavelength of the formation of these products and their column densities of formation. We also studied the ratio of the column densities of HCN and HNC as a function of photolysis wavelength and duration of irradiation. The mechanisms of formation of the main products are discussed. Our results have implications for the radiatively assisted syntheses of nitrile molecules in the interstellar medium and on icy surfaces of planets and satellites in the solar system.