COHERENT NUCLEAR MOTIONS IN LIGHT-HARVESTING PIGMENTS AND DYE MOLECULES, PROBED BY ULTRAFAST SPECTROSCOPY

The temporal evolution of the transient absorption response of light-harvesting antennae and dye molecules was studied. Using 40-90 fs pulses coherent nuclear motions were observed in intact membrane-bound photosynthetic light-harvesting pigment-protein complexes, bacteriochlorophyll a monomer and dye molecules in solutions, Computer simulations based oh the harmonic Franck-Condon approximation and the Langevin equation describe qualitatively well the wavelength dependence of the oscillations of the mode when exciting and probing in the blue side of the spectrum.