EXCITATION DELOCALIZATION OVER THE WHOLE CORE ANTENNA OF PHOTOSYNTHETIC PURPLE BACTERIA EVIDENCED BY NONLINEAR PUMP-PROBE SPECTROSCOPY

Anomalously high values of photoinduced absorption changes were reveal ed in the antenna of photosynthetic purple bacteria, They were found t o be 4-16 times greater at the bleaching peak of the antenna than at t he bleaching peak of the BChl dimer of the reaction center, This is di rect proof of excitation delocalization over many pigment molecules, C alculations according to the model of exciton delocalization over all core antenna BChls allow one to explain the observed phenomenon.