Jet-Cooled Emission Spectra of the Xylyl Radicals

Spectroscopic Identification of Isomeric Trimethylbenzyl Radicals Generated from 1,2,3,4-Tetramethylbenzene

“…Figure 1 shows a portion of the vibronic emission spectrum of the benzyl-type radicals formed by the corona discharge of precursor 1,2,3,4-tetramethylbenzene, prehnitene in which many of the strong bands are observable with a very good S/N in the region of 19000-22000 cm , the substitution of the methyl group(s) into the benzene ring showed red-shifted origin bands, as listed in Table 1. For mono-substituted benzyl radicals, the o-, m-, and p-xylyl radicals 13 showed the origin bands at 21345, 21485, and 21700 cm from the benzyl radical, respectively, in the D1 → D0 electronic transition.…”

“…Bandshape analysis of high-resolution emission spectra satisfactorily resolved controversial vibronic assignments of p-xylyl radical. 10 In addition, torsional analysis of the methyl rotor in xylyl radicals has been carried out by Lin and Miller. 11 Selco and Carrick 12,13 have assigned many bands in the vibronic emission spectra of benzyl and xylyl radicals.…”

Formation of Difluorobenzyl Radicals from 2,3,4-Trifluorotoluene in Corona Excitation

“…3 With the background of the delocalized π electronic structure of the benzyl radical, many benzyl-type radicals have been extensively studied to explain their substitution effect by employing a variety of experimental schemes, in which the technique of corona excited supersonic expansion (CESE) has been proved to be a useful tool for the observation of the jet-cooled benzyltype radicals. [4][5][6][7][8][9][10] In this group, we significantly improved the generation efficiency of benzyl-type radicals by upgrading the nozzle system 11 for the spectroscopic observation of transient species.…”

Vibronic Emission Spectra of Jet-Cooled o-Cyanobenzyl Radical

“…Of many benzyl-type radicals, the assignments of vibronic bands of xylyl radicals have been extensively carried out to determine the vibrational mode frequencies in the ground electronic state. 4,5 The torsional contribution of the methyl rotor has been obtained from simulation of the rotational contours of the high resolution Fourier transform emission spectra. 6 As for halogen-substituted benzyl-type radicals, many vibrational modes of fluorobenzyl radicals in the ground electronic state have been determined using different spectroscopic techniques.…”

“…4 The metastable He atoms produced in a corona discharge transfer the excitation energy to the precursor through collisional process to form benzyltype radicals by breaking off α-hydrogen bond of methyl group.…”