Visible emission spectroscopy of jet-cooled chloro-substituted 2-methylbenzyl radicals.

Graphical abstract Highlights • We characterized the radical species generated from the corona discharge of 3- and 4-chloro-o-xylenes. • We identified the formation of the 3-, 4-, 5-, and 6-chloro-2-methylbenzyl radicals from analysis of the observed spectra. • We determined the spectroscopic data of the benzyl-type radicals produced in this work. • We discussed the distribution of the electronic transition energies of 4 isomeric radical species. Abstract Four isomeric chloro-substituted 2-methylbenzyl radicals were generated from the corona discharge of 3- and 4-chloro- o -xylenes seeded in a large amount of He carrier gas using a technique of corona excited supersonic expansion coupled with a pinhole-type glass nozzle. The observed visible vibronic emission spectra were analyzed to identify the radical species produced in the discharge, from which the production of the 3-, 4-, 5-, and 6-chloro-2- methylbenzyl radicals was confirmed. In addition, we determined the D 1 → D 0 electronic transition energies and vibrational mode frequencies in the D 0 state of the isomeric chloro-substituted 2-methylbenzyl radicals. [ABSTRACT FROM AUTHOR]