Excitation-induced polarization decay in the plant light-harvesting complex LHCII

► Polarized pump-probe gives information on energy transfer between isoenergetic Chlorophyll. ► Energy transfer in LHCII at 77 K leads to a decay of anisotropy to zero upon 652 and 662 nm excitation. ► Target model yields several Chlorophyll b and a species with different spectra or anisotropy values. ► The memory of polarization is lost with a (3.3-5.0 ps)−1 rate over the whole Qy range. ► The slowest depolarization rate mainly reflects equilibration between the three monomers of LHCII.