Berlin 2005 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 25: Biological systems I

CPP 25.2: Talk

Tuesday, March 8, 2005, 14:15–14:30, TU C230

Multivariate Analysis of Single-Molecule Spectra: Surpassing Spectral Diffusion — •Clemens Hofmann¹, Hartmut Michel², Marin van Heel³, and Jürgen Köhler¹ — ¹Experimental Physics IV and BIMF, University of Bayreuth, 95440 Bayreuth, Germany — ²Department of Molecular Membrane Biology, Max-Planck Institute of Biophysics, Frankfurt, Germany — ³Department of Biological Sciences, Imperial College London, London SW7 2AY, United Kingdom

The full exploitation of single-molecule spectroscopy in disordered systems is often hampered by spectral diffusion processes of the optical transitions due to structural fluctuations in the local environment of the probe molecule which leads to temporal averaging of the signal. Multivariate statistical pattern recognition techniques, originally developed for single-molecule cryo-electron microscopy, allow us to retrieve detailed information from optical single-molecule spectra. As an example, we present the phonon-side band of the B800 excitations of the LH2 complex from Rhodospirillum molischianum, revealing the electron-phonon coupling strength for these transitions. The measured Debye-Waller factors, ranging from 0.4 – 0.8, fall in the regime of weak electron-phonon coupling.