ELECTRONIC AND INFRARED SPECTROSCOPY OF BENZYL RADICALS IN NEON MATRICES.

Author Institution: Union Carbide Research InstituteBenzyl radicals were prepared by the flash vacuum pyrolysis of benzyl bromide at $1000^{\circ}C$ and condensed with neon at $4^{\circ}K$. Spectra were obtained in the ultraviolet, visible and infrared regions. The (0,0) bands showed only very small shifts from their gas-phase values (e.g. $32,724 cm^{-1}$ in matrix, $32,745 cm^{-1}$ in gas). The following electronic transitions were observed $\begin{array}{ccc}Transition&(0,0) band\, in\, cm^{-1}&No.\, of\, vibrational\, bands\\ \qquad2\, ^{2}A_{2}\leftarrow 1\, ^{2}B_{2}&32,724&14\\ \qquad1\, ^{2}A_{2}\leftarrow 1\, ^{2}B_{2}&22,003&15\\ \qquad1\, ^{2}A_{2}\leftarrow 1\, ^{2}B_{2}&22,001&30\\ ({?})\quad 3\, ^{2}B_{2}\leftarrow 1\, ^{2}B_{2}&40,750&\qquad\qquad\qquad1 (very\, broad)\end{array}$ The infrared spectra showed the presence of the dimerization product bibenzyl. The correspondence between the infrared frequencies and the ground state vibrational frequencies obtained from the fluorescence spectra will be discussed