Doctor Oliver Kuehn
Physical and Theoretical Chemistry
Freie Universitat Berlin
Berlin, Germany

Monday, March 11, 2002
3:00 pm (CT)
4269 Beckman Institute

Abstract

The availability of atomic scale information on several light-harvesting pigmen protein complexes has triggered a host of experimentalandtheoreticalinvestigationsdirected towards the understanding of the initial steps of photosynthesis. In this contribution I will discuss a density matrix approach to the ultrafast nonlinear spectroscopy of antenna systems which provides the adequate tool for monitoring excitation energy flow and dephasing processes in real time. A model Hamiltonian will be derived which is based on the concept of Frenkel excitons interacting with the vibrational degrees of freedom of the complex. Within general relaxation theory this interaction is described by a spectral density which can be extracted from experimental data. Results will be presented in particular for the peripheral antenna complex LH2 of purple bacteria such as Rps. acidophila.

Tea and coffee will be served in R3151 Beckman Institute at 2:15pm.