Light-intensity-modulated photocurrents when intermediate particles are removed by diffusion

Frequency spectra of the photocurrent in the modulated illumination conditi ons are calculated with allowance made for the removal of intermediate part icles from the surface by diffusion. The shape of calculated complex-plane plots of the photocurrent is essentially dependent on the contribution made by diffusion to the total photoprocess. The calculations are compared with experimental data for a passive iron electrode in an alkali solution. It i s shown that illuminating the iron electrode covered by an oxide film leads to the oxidation of the Fe2+ ions present in the film and to the diffusion removal of oxidation products (Fe3+) from the surface with their simultane ous reduction.