The interaction of solutes with their environments

The origins of electronic spectral broadening in solutions, glasses and proteins are discussed via three pulse stimulated echo peak-shift measurements. Spectral densities for dye molecules in polar solutions are presented and discussed in terms of molecular models for the dynamics. The breakdown of the harmonic bath picture at low frequencies is presented. Finally, echo measurements on light harvesting complexes of purple bacteria are presented and it is shown that the energy transfer timescale can be obtained from peak-shift measurements.