Burning of a narrow spectral hole at 1.7 K in the absorbance band of the primary electron donor of Rhodopseudomonas viridis reaction centers with blocked electron transfer

Abstract

Burning of spectral holes within the absorption band of the primary electron donor P in reaction centers of Rhodopseudomonas viridis is studied using selective excitation at 1014 nm and 1.7 K. A narrow (≤ 1.0 cm −1) spectral hole with relatively weak electron-phonon and vibronic coupling is burned if the intermediary electron acceptor I is pre-reduced. The hole is broadened up to ∼90–150 cm −1 if I is neutral and the electron-transfer chain is open. Broadening of the hole is discussed in terms of the fast (∼70–110 fs) electron hopping between P* and P +BL − (BL, bacteriochlorophyll monomer in L protein subunit).