Distribution of excitation energy in photosynthesis: quantification of fluorescence yields from intact cyanobacteria

Fluorescence emission spectra of intact cyanobacteria in state 1 and state 2 were determined at 77 K. Spectra were obtained from samples held in a rotating cuvette designed to average sample inhomogeneities and allow accurate fluorescence yield comparisons without normalization to intrinsic or added fluorophore emission peaks. Emission spectra obtained for excitation in the chlorophyll a (Chl a) and phycobilisome absorption regions were …