Solvent and concentration effects on the steady state fluorescence of fluorenone

TLDR: In this paper, the effects of fluorenone concentration in various solvents in the range 10 −6 −10 −3 M on the spectral properties are discussed, and the mechanism of excimer formation has been explained.

Abstract: The electronic absorption and steady state fluorescence spectra of fluorenone in the regions 280–340 and 320–420 nm respectively have been obtained at room temperature for various concentrations in a series of non-polar and polar solvents. The effects of fluorenone concentration in various solvents in the range 10 −6 −10 −3 M on the spectral properties are discussed. In addition to the monomer fluorescence, we have also observed another fluorescence band at longer wavelength in the region 420–600 nm which has been ascribed to excimer formation. The monomer and excimer fluorescence lifetimes of fluorenone in typical solvents such as benzene and acetonitrile have been determined experimentally. By combining our results of steady state fluorescence and measurements of fluorescence lifetimes with previously reported studies of laser-induced fluorescence, the mechanism of excimer formation has been explained. The absence of excimer formation in hexane, cyclohexane and alcohols is discussed.