Double-Channel Photoionization Followed by Geminate Charge Recombination/Separation

Abstract

The photoionization of perylene by tetracyanoethylene (TCNE) in liquid solutions is reconsidered within the corrected energy scheme for a double channel electron transfer: to the ground and excited states of the produced ion pair. The complex space dependence of a total (double channel) rate of multiphonon transfer is specified and compared to the recently proposed monoexponential model. The fitting of the forward electron transfer (ionization) is essentially improved, and the real electron coupling and tunneling parameters are firmly established. The same has been done for the geminate recombination/separation kinetics, accounting theoretically for the hot recombination experienced by 2/3 of the initially produced ion pairs. Only 1/3 of them is left for subsequent thermal recombination and even less are left for their separation into free ions. The yields of the latter, strongly dependent on the initial concentration of TCNE, are brought into reasonable coincidence with the theoretical predictions by a renormalization of the empirically calibrated ion densities especially at large concentrations. Altogether, this is a precedent spin-less treatment of photoionization well-fitted to the experimental data at all times (from the excitation until charge separation), with a single set of varying parameters.