Observation of vibronic emission spectrum of jet-cooled 2,4-difluorobenzyl radical in a corona excitation

The jet-cooled 2,4-difluorobenzyl radical was generated and vibronically excited in a corona excited supersonic expansion from 2,4-difluorotoluene seeded in a large amount of inert carrier-gas helium. The well-resolved vibronic emission spectrum of the jet-cooled 2,4-difluorobenzyl radical was recorded in the visible region with a long-path monochromator and analyzed to obtain an accurate measurement of the electronic energy of the D1 → D0 transition and vibrational-mode frequencies in the ground electronic state by comparison with those of 2,4-difluorotoluene as well as those from an ab initio calculation.