Infrared and Ultraviolet Spectroscopic Study of the Products of the Vacuum-Ultraviolet Photolysis of Methane in Ar and N2 Matrices. The Infrared Spectrum of the Free Radical CH3

Abstract

The vacuum‐ultraviolet photolysis of methane in an argon or a nitrogen matrix at 14°K leads to the formation of a sufficient concentration of the methyl radical for observation both of its 1500‐Å electronic transitions and of its out‐of‐plane deformation fundamental, which appears at 611 cm⁻¹ for CH₃ trapped in a nitrogen matrix. The value observed for this fundamental of CD₃ is in reasonable agreement with the value previously derived from analysis of the 2160‐Å band system. Isotopic substitution studies support the assignment of the 611‐cm⁻¹ feature to ν₂ of CH₃. Data are consistent with the previous report of a planar structure. Evidence is presented suggesting that CH₃ may rotate in an argon matrix. Although CH₂ has not been directly observed, an appreciable concentration of CH₂N₂ appears in the N₂ matrix experiments. Three electronic transitions of CH are observed in the argon matrix experiments, and there is evidence for the production of a small concentration of C atoms.