Earlier researches on the mechanism of oxygen evolution: A personal account

A brief overview is given of the research which led to the discovery of the period-4 oscillations of the flash-induced oxygen production and which is the basis of the generally accepted Kok's model for water splitting and oxygen evolution.In this paper I discuss the earlier work of the groups of Robert Emerson, James Franck, C. P. Whittingham, and myself in relation to the development of new techniques for the detection of photosynthetic oxygen evolution. Also discussed are various hypotheses and speculations related to the concept of a priming photoreaction which is required for oxygen evolution. Finally, I discuss my long scientific collaboration with Bessel Kok which led to the elaboration by Kok of the classical model in which the formation of oxygen requires the sequential accumulation of four positive charges on the same photochemical center.