Visible and near-IR fluorescence of aromatic radical cations in micellar solutions, BF 3—trifluoroacetic acid, γ-Al 2O 3 and SiO 2Al 2O 3

Abstract

This paper describes studies of the fluoresence spectra of radical cations. Direct visible excitation of the radical cations of 1-pyrenecarboxaldehyde produced on γ-Al 2O 3 and SiO 2Al 2O 3 surfaces leads to an identical visible emission band at 520 nm. The radical cations of N, N, N′, N′-tetramethylbenzidine in a micellar solution of sodium dodecyl sulfate and on γ-Al 2O 3 exhibit near-IR emission spectra with maxima at 1100 and 1250 nm. The radical cations of perylene in 22 mol.% (BF 3H 2P)—trifluoroacetic acid, γ-Al 2O 3 and SiO 2Al 2O 3 exhibit two emission bands at 820 and 910 nm. The radical cation of tetracene exhibits emission bands at 910 and 1030 nm. Emission spectra of these radical cations all exhibit good mirror images of their corresponding absorption spectra. The studies provide an additional sensitive means of identifying radical cations on solid surfaces.