Observation of vibronic emission spectra of difluorobenzyl radicals: Jet-cooled 2,5-difluorobenzyl radical

We report the first spectroscopic observation of jet-cooled 2,5-difluorobenzyl radical produced from 2,5-difluorotoluene seeded in a large amount of inert carrier gas He and vibronically excited in a corona excited supersonic expansion using a pinhole-type glass nozzle. The visible vibronic emission spectrum of the jet-cooled 2,5-difluorobenzyl radical recorded with a long path monochromator was analyzed to obtain an accurate measurement of the electronic transition between the D1 and D0 electronic states. The vibrational mode frequencies in the ground electronic state were determined by comparison with those of 2,5-difluorotoluene as well as those from an ab initio calculation.