Ab initio and spectroscopic study of dimethylbenzyl radicals in a corona excited supersonic expansion

Chang soon Huh

We report the spectroscopic and ab initio and spectroscopic evidence of the 2, 3- and 2, 6-dimethylbenzyl radical in corona excitation. The electronically hot but jet-cooled 2, 3- and 2,6-dimethylbenzyl radical has been produced from precursor 1, 2, 3-trimethylbenzene seeded in large amount inert carrier gas helium by using the technique of corona excited supersonic expansion (CESE) with a pinhole-type glass nozzle. The vibronic emission spectrum of the 2, 3- and 2, 6-dimethylbenzyl radicals were recorded with a long path monochromator in the D1 → D0 electronic transition in the visible region. Ab initio calculation of the ground-state benzyl radical have been carried out with density functional method and the complete basis set model. The observed spectrum is consistent with the result of vibrational frequencies of the ab initio calculation and the benzyl radical ground state reaction mechanism through the hydrogen migration is presented. Furthermore, the ab initio calculation explains the benzyl radical generation mechanism in the excited state through the anti-bonding energy surface. By Additional help of the substitution effect of methyl substituted benzyl radicals, we could identify the jet-cooled 2, 3- and 2, 6-dimethylbenzyl radicals formed in corona discharge of 1, 2, 3-trimethylbenzene.