Red pool chlorophylls of photosystem I of the cyanobacterium Thermosynechococcus elongatus: A single-molecule study

Photosystem I reaction centers of the cyanobacterium Thermosynechococcus elongatus are investigated using single-molecule spectroscopy and observations reveal that only a few chlorophylls are responsible for the photoemission from the Photosystem I (PSI) trimer. This implies an efficient energy transfer between the monomeric subunits of the PSI trimer and shows an efficient triplet state quenching of the red chlorophylls.