Barrierless Electron Transfer in a Photosynthetic Reaction Center Model

Abstract

Vibrational spectroscopy is the ultimate tool to reveal whether any donor-acceptor system is truly delocalized and therefore characterized by a single-welled potential energy surface, or if it is marginally localized with a barrier that defines two minima. Our femtosecond IR absorption investigations on cyanide-bridged mixed valence systems show a broad, intense and downshifted CN vibration signature, revealing, for the first time, an asymmetric, fully delocalized Class III photoinduced mixed valence system