Triplet Delocalization over the Reaction Center Chlorophylls in Photosystem II.

The triplet state of chlorophyll formed by charge recombination in photosystem II (PSII) is a precursor of harmful singlet oxygen. Although main localization of the triplet state on the monomeric chlorophyll, Chl, at cryogenic temperatures has been suggested, how the triplet state is delocalized on other chlorophylls remains unclear. Here, we investigated the distribution of the triplet state of chlorophyll in PSII using light-induced Fourier transform infrared (FTIR) difference spectroscopy.