Hannover 2013 – scientific programme

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MO: Fachverband Molekülphysik

MO 14: Poster 1: Cluster, Femtosecond Spectroscopy

MO 14.18: Poster

Tuesday, March 19, 2013, 16:00–18:30, Empore Lichthof

SVD analysis for the time-resolved study of the electron transfer in photosynthetic reaction center of Rhodobacter Sphaeroides — •Jeff Michelmann, Pablo Nahuel Dominguez, Matthias Himmelstoß, and Wolfgang Zinth — Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians-Universität, Oettingenstr. 67, D-80538 München, Deutschland

The purple bacteria, Rhodobacter Sphaeroides, contains a very simple and well studied reaction center. Upon light absorption it can convert the incoming energy into chemical energy with high efficiency via electron transfer and charge separation. Ultrafast spectroscopy gives insight into its electron transfer dynamics in the picoseconds regime. Current methods to analyze time-resolved absorption data of this process involve different approaches, e.g. a direct multiexponential fit of the original data and a fit of the basis vectors of the Single Value Decomposition (SVD) matrix. SVD is a powerful filtering mechanism capable of creating a smooth output signal by removing smaller SVD components. If not applied correctly, however, small signal amplitudes may be rejected and corresponding physical processes are lost. With new developments in subpicosecond pump-probe experiments we recorded data on reaction centers which can be analyzed without any smoothing algorithm. A multiexponential fit based on a sequential rate model has been applied directly. The results confirm the existence of an intermediate radical pair state P+B- with a decay time of 0.9ps. Based on different data evaluation procedures we discuss the significance of the 0.9ps kinetic component.