title: Excitation transfer between photosynthetic units: the 1964 experiment.
abstract: We review here the background and the experiments that led to the concept of excitation energy transfer among photosystem (PS) II units. On the basis of a kinetic analysis of oxygen evolution and chlorophyll a fluorescence yield, the authors showed, in 1964, that the PS II photochemical reaction involved in the formation of oxygen is not a first-order process. We concluded that excitation energy localized in a 'photosynthetic unit' including a reduced primary acceptor is transferred with a high probability to neighboring PS II units. Here, the beginnings and the original data of this topic are presented.
authors.affiliation: Institut de Biologie Physico-Chimique, Centre National de la Recherche Scientifique (CNRS) UPR1261, 13 Rue Pierre et Marie Curie, 7505, Paris, France, ajoliot@ibpc.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Joliot
authors.forename: Anne
authors.initials: A
authors.lastname: Joliot