Room temperature fluorescence from arylmethyl radicals in solution

Abstract

We report temperature fluorescence spectra of the triphenylmethyl, diphenylmethyl, and benzyl radicals from two-pulse excitation of the corresponding arylmethyl chloride in methylcyclohexane. For the triphenylmethyl radical, a lowest excited state (D 1) lifetime of (4.5±0.5) ns is determined. It is alsodemonstrated that rearrangement of this D 1 state to a species of λ max 490 nm competes with its radiative relaxation. These findings are consistent with a thermally activated photochemical process for triphenylmethyl (D 1) radicals, as proposed by previous workers.