By means of a pinhole-type glass nozzle designed for supersonic jet expansion along with corona discharge, vibronically excited but jet-cooled isomeric benzyl-type radicals were generated from the precursor 3-fluoro-o-xylene. The visible vibronic emission spectrum was recorded from the discharge system with a long-path monochromator. From an analysis of the spectrum observed, we identified the formation of two isomers, 2-methyl-3-fluorobenzyl and 2-methyl-6-fluorobenzyl radicals in the corona discharge of precursor, and determined for the first time the electronic energy in the D-1 -> D-0 transition and vibrational mode frequencies in the D-0 state for both isomers. (C) 2013 Elsevier B. V. All rights reserved.