Fluorescent solvent excited states from hole-electron recombination in cis- and trans-decalin irradiated with high energy electrons

Abstract

The formation of the fluorescent solvent excited states in cis- and trans-decalin in the presence of various electron and hole scavengers has been studied by measuring the fluorescence resulting from pulsed irradiation. In order to be able to determine the effect of the charge scavengers on the yield of formation of the fluorescent excited state the quenching of the excited state by the scavengers has been studied in detail. Diffusion coefficients of the solutes have been determined and reaction radii for the quenching reactions are given. The ratio of the depression of the yield of formation of fluorescent excited states and the yield of charge scavenging has been found to be approx. 0.9 for both electron and hole scavengers and shows a tendency to decrease at higher concentrations. The results are consistent with earlier independent measurements of the mobilities of electron holes and excess electrons. The ratio of approx. 0.9 represents the average probability of singlet excited state formation from ion recombination for the relatively longer lived ion pairs, which indicates a relatively large contribution of single ion pairs. The average probability of singlet formation from the shorter lived ion pairs is expected to be lower.