COMPUTER-ANALYSIS OF PHOTOINDUCED CHARGE-TRANSFER AT THE ITIES IN PROTOPORPHYRIN-QUINONE SYSTEMS

A computer analysis of the photocurrent kinetics in protoporphyrin IX-quinone systems (studied experimentally in a previous publication) has been carried out. Good agreement between the experimental and calculated kinetics as well as other features (decay kinetics, effects of the absorption coefficient of the solution, alpha and light flux I0) of the photocurrent in protoporphyrin-quinone systems was obtained by consideration of the transfer of both semiquinone radical anions and stable charge carriers which are formed in the oxidation reaction of B(Ph)4- by radical cations of protoporphyrin. The dependence of the photocurrent i on the interfacial potential DELTAE has been simulated. The calculated DELTAE-i curve is close to the experimental one. The diffusion approach was found to be the most convenient among several theoretical methods for the description of the photocurrent kinetics for this case. The kinetic parameters of the process were estimated from the linear dependence of the logarithm of the interfacial transfer rate constant, In k(tr), on the interfacial potential difference.