FEMTOSECOND VIBRATIONAL DYNAMICS AND RELAXATION IN THE CORE LIGHT-HARVESTING COMPLEX OF PHOTOSYNTHETIC PURPLE BACTERIA

Using 50 fs light pulses we have observed the wavelength dependent pha se shifts of oscillatory transients in the transient absorption kineti cs of the LH1 complex from purple bacteria at 77 K. We applied the den sity operator formalism in Liouville space in combination with Redfiel d relaxation theory to calculate the transient absorption response of the model system consisting of three electronic states and one vibrati onal mode linearly coupled to the thermal bath. This enabled us to est imate relative displacements of the potential energy surfaces in the h igher excited states of the LH1 complex and investigate the influence of coherence transfer processes.