Unusual temperature quenching of bacteriochlorophyll a fluorescence in FMO antenna protein trimers

Thermally induced quenching of fluorescence in the trimeric Fenna-Matthews-Olson antenna complex starts at unusually low temperatures as compared to the isolated BChl a molecules in common matrixes. Close spacing of the trimer exciton states within the lowest-energy manifold of absorbing states is proposed mainly responsible for this effect.