Triplet State ADMR of Bacterial Reaction Centers at Low Transition Frequencies

Abstract

Absorption detected magnetic resonance (ADMR) had been used extensively to characterize triplet states of bacteriochlorophyll (BChl) molecules in photosynthetic antenna and reaction center (RC) complexes [1]. In bacterial RCs the triplet state is located on the primary donor and either localized on the L-side monomer in the case of Rhodopseudomonas (Rps.) viridis or delocalized over both parts of the dimer in the case of Rhodobacter (Rb.) sphaeroides R26 [2]. Triplet states with slightly different zero field splitting values have been found for the primary donor [3] but no other triplet state had been observed so far in RC preparations (with the possible exception of trivial preparational artifacts). In this contribution we present ADMR experiments on the triplet state of the radical pair 3[Pg860 + BH−] which recombines by populating the primary donor triplet state. Parts of these results have already been published in [4].KeywordsTriplet StateMicrowave PowerPrimary DonorZero Field SplittingBChl MoleculeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.