Spectroscopic Study of the Vacuum-Ultraviolet Photolysis of Matrix-Isolated HCN and Halogen Cyanides. Infrared Spectra of the Species CN and XNC

Abstract

Vacuum‐ultraviolet photolysis of HCN isolated in Ar and N₂ matrices at 14°K is found to lead to the production of HNC in concentration sufficient for direct infrared observation of all three vibrational fundamentals. The spectrum of this species is found to be appreciably perturbed by the presence of N₂. The force constants and thermodynamic properties of HNC have been revised to the values appropriate to this species in an environment free of perturbation by an adjacent N₂ molecule. The free radical CN is also produced in these systems in concentration sufficient for direct observation not only of the B(²Σ⁺)—X(²Σ⁺) transition but also of the ground‐state vibrational fundamental. Isotopic data supporting this identification are presented. Upon vacuum‐ultraviolet photolysis of matrix‐isolated FCN, two infrared absorptions appear which can be identified with the stretching fundamentals of the species FNC. In analogous experiments on the species ClCN and BrCN, infrared absorptions tentatively assigned to ClNC and BrNC have been observed.