484—Photosensitive lipid membranes: Part II. The collodion-oleic acid,methylene blue sensitized membrane in aerated KCl solutions. Evidence for the intervention of singlet oxygen in the photoreaction mechanism

The photoresponse of lipid membranes of oleic acid, sensitized with methylene blue and immobilized by collodion, was examined in acrated, aqueous KCl solutions. Deposited on suitable metal electrodes, these membranes can reach considerable photovoltages, of the order of ?360 mV, depending mainly on the electrolyte concentration, the highest values being obtained with concentrated (2M) KCl solutions.In the presence of a typical singlet oxygen quencher, such as N₃Na, the photoresponse is diminished in a quantitative manner, whereas the presence of D₂O, as singlet oxygen lifetime promoter, increases the photoresponse in KCl 1 × 10^?1M solutions. Thus, the intervention of singlet oxygen in the photoreaction mechanism is indirectly proved.