The question of the intermediate state P⁺Chl^‐in bacterial photosynthesis

Abstract

In bacterial photosynthesis it has been proposed that an electron is transferred from the excited singlet state (P∗) of theprimary electron donor first to a bacteriochlorophyll (BChl) molecule, generating a P + Chl charge‐transfer state, and that BChl ‐ subsequently (4–7 ps) transfers an electron to a bacteriopheophytin molecule. Here we review the evidence for and against the intermediacy of P + BChl ‐ and present picosecond transient absorption and kinetic data that bear on this point. We conclude that there is no convincing evidence that P + BChl is a kinetically or spectrally resolved intermediary state in the charge separation process.