Study of the reactions of geminate ions in irradiated scintillator, hydrocarbon solutions using recombination fluorescence and stochastic simulations

The fluorescence from electron beam pulse irradiated solutions of scintillators in n-hexane and cyclohexane has been measured. The experimental fluorescence vs time is compared to calculations utilizing a stochastic Monte Carlo model, in which three different distribution functions were tested to describe the initial electron-solvent{sup {sm bullet}+} separation distance. This comparison indicates that the recombination fluorescence is markedly affected by fast reactions of the solvent radical cations, most likely proton transfer to the solvent, which prohibit eventual formation of the fluorescent state of the scintillator via ion recombination reactions. Results bearing on the contribution of energy transfer from the solvent-excited state to the scintillator are also presented. Measured G values of the fluorescent state of the scintillator are considerably lower than those calculated from the model, and possible reasons for this are discussed.