Knowledge Bank

Of all the arylmethyl radicals, only the prototype, benzyl or phenylmethyl, has been observed by laser-induced fluorescence in the gas phase. The diphenyl- and triphenylmethyl radicals have been studied only in condensed phase by visible absorption and electron paramagnetic resonance. Further phenyl substitution of the benzyl radical raises several questions about the structures of the arylmethyl radicals. As a step toward the understanding of these radicals, we report for the first time the observation of vibrationally-resolved electronic spectra of cold diphenylmethyl, chlorodiphenylmethyl, diphenylethyl, and triphenylmethyl radicals in a free jet expansion. Convincing arguments as to the nature of the spectral carriers along with precise origin frequencies and fluorescence lifetimes will be presented