The Potential of Photoactive Cells Containing Fluorescent Electrolytes

Abstract

Variation with time of illumination of the potential of a cell containing rhodamin B dissolved in absolute alcohol.-A theory of the variation of potential with time has been developed for the photoactive cell. It is assumed that the exciting light produces a chemical change in the electrolyte. Allowing for the effects of diffusion the expressionwhere E is the e.m.f., T is time of illumination, t is time after illumination ceases, / is the intensity of illumination, and K and B are constants, has been derived. By the use of a cell with platinum electrodes containing Rhodamin B in absolute alcohol and illuminated with monochromatic light, results in good agreement with the theory are secured. Diffusion is shown to play an important part. Goldmann's theory is shown to be inadequate. No "limiting potential,"independent of the intensity of illumination, was found. No evidence was found which indicated the presence of the Hallwachs photo-electric effect.