Time-resolved effects of an electric field in recombination fluorescence

Quenching of the recombination fluorescence by an external electric field was investigated in hexane, tetradecane, and aqualane solutions of p-terphenyl and 2.5-diphenyloxazole irradiated with X-rays. The kinetics of the recombination fluorescence I(E,t) was measured in a nanosecond time scale and the quenching-efficiency curves Q(E,t) = 1 - I(E,t)/I(0,t) were plotted. The dependence Q(E,t) was shown to have the specific character Q(E,t) = f(pt), where p = AE{sup 2}D/r{sub c}{sup 2}. Here A is a constant dependent on the initial-distance distribution function of the charges, E is the electric field strength, D is a mutual diffusion coefficient of the recombining ions, and r{sub c} is the Onsager radius. The quadratic dependence of the parameter p on the electric field strength was shown to be a consequence of the diffusion-controlled reaction of ion recombination.