Vacuum UV Photolysis of Benzene in Solid Nitrogen

The photolysis of C₆H₆/N₂ matrix samples at 10 K under 121.6 and 175 nm was investigated, and the observed IR lines were identified by comparison with literature results, expected photochemical trends, and isotopic substitution experiments. Under 175 nm photolysis, photoproducts were identified, including isomers of benzene, phenyl (Ph) radicals, alkenes and/or alkynes, and pure linear carbon clusters (C₃ and C₅); however, N-bearing hydrocarbons were not detected. In contrast, several new IR signatures were observed upon 121.6 nm photolysis; some of these signatures were readily identified as absorptions of CN, HCNC, NC₆N, and phenylnitrene (PhN), while the other unknown lines observed in the typical C≡N stretching region were expected to correspond to linear nitriles. By further warming the sample to 30 K, the line intensities of PhN decreased, and the IR lines of anilino radicals (PhNH) and aniline (PhNH₂) were observed, indicative of the recombination of H atoms with primary photofragments via diffusion.