PHOTOELECTRON INJECTION INTO DILUTE ELECTROLYTE-SOLUTIONS .1. METHODOLOGY

A general algorithm for the numerical solution that describes the diff usion and reactions of particles in an arbitrary potential was used to calculate the photodiffusion currents in dilute electrolyte solutions in terms of the exact Gouy-Chapman expression for the diffusion poten tial phi(x). The solution has been obtained for the simplest case when the product of the capture of solvated electrons, generated by photoi njection, is a neutral radical. The limited applicability of the expon ential approximation of the phi(x) potential has been demonstrated. Wh en the electrolyte solution is dilute, the characteristic time of the return of solvated electrons e(s)(-) to the electrode increases by 3-6 orders of magnitude within the negative potential range. Thus, when t he scavenger concentration is 10(-4)-10(-3) M, it can fully capture e( s)(-). The calculation results have been compared with those of experi ments performed in diluted aqueous solutions of NaF (10(-3)-1 M) at wa velengths of lambda = 428-193 nm. The mean distances determined betwee n e(s)(-) and the photoelectrode are in fair agreement with the previo us data obtained for concentrated aqueous electrolyte solutions. We ha ve also found the mean distances, photoinjection threshold and full ph otoinjected charge in methanol. The effect of the intensity of light o n the value of photo-induced charge has also been demonstrated.