PARENT SESSION

Symposium S5D Emerging techniques and systems
Wednesday September 1st, 2004 10:20 AM-12:20 PM Room 510A
Chair: Conrad Mullineaux
Co-Chair: Barry Osmond

The electronic structure of light-harvesting complexes as revealed by single-molecule optical spectroscopy. Thijs Aartsma^*,1, ¹ Leiden University, Leiden, The Netherlands

ABSTRACT- The technique of single-molecule optical spectroscopy has been applied to a variety of light-harvesting complexes from purple photosynthetic bacteria in order to establish a relationship between their optical properties and molecular structure. Optical spectra of individual molecules have the advantage that they are free of averaging effects that dominate ensemble measurements. Therefore, spectroscopic details can be discerned which are obscured when studying these complexes by conventional spectroscopic methods. The spectroscopic fine-structure that can be observed this way in the spectra of light-harvesting complexes are determined by relatively strong intermolecular interactions, and therefore can be correlated with structural properties. We will present an overview of the results that have been obtained recently. In particular, we will discuss the effect of static disorder, spectral diffusion, and light-induced conformational changes. It is found that significant differences exist between various types of light-complexes that look rather similar at first sight. These differences can be explained on the basis of structural details.

KEY WORDS: purple bacteria, single molecules, light-harvesting , excitons