Two-dimensional electronic photon-echo spectroscopy of photosynthetic complexes

• Applicant: Professor Dr. Wolfgang Domcke
• Subject Area: Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
• Term: from 2006 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 25637392

• Final Report Year: 2010

Final Report Abstract

We have developed numerically efficient algorithms that allow accurate simulations of a large variety of nonlinear time- and frequency-resolved spectroscopic signals. Of particular relevance is the equation-of-motion phase-matching approach (EOM-PMA), which has been developed by Gelin, Egorova and Domcke. It allows an efficient evaluation of any A'^-wave-mix ing signal for complex system Hamiltonians and ultrafast laser pulses of any duration. The applications realized in this project include pumi>probe spectroscopy, time-resolved fluorescence, as well as homodyne and heterodyne photon-echo spectroscopy - a four-wave-mixing (4WM) scheme. In particular, we have focused on two-dimensional (20) photon-echo signals. Recent 2D photon-echo experiments reveal that quantum coherence may play a non-negligible role in the energy-trans fer mechanism of photosynthetic complexes. We have addressed 2D photon-echo spectra of the Fenna- Matthews-Olson (FMO) photosynthetic complex. Our methods allow us to accurately simulate the experimental signals, thus testing various models of the FMO complex, and to study their adequacy by direct comparison to the experiment. We have shown that the previously employed exciton model of the complex cannot reproduce the observed quantum coherences, although the experimental line shapes can be satisfactorily reproduced. These findings reveal that a more complicated excited-state dynamics takes place than previously thought. We have proposed a more sophisticated model that explicitly accounts for vibrational dynamics as an additional mechanism which can give rise to quantum coherences in the 2D photon-echo spectra.

Publications

• Analysis of cross peaks in two-dimensional electronic photon-echo spectroscopy for simple models with vibrations and dissipation, J. Chem. Phys. 126, 074314 (2007)
  D. Egorova, M. Gelin, W. Domcke
  
• Analysis of vibrational coherences in homodyne and twodimensional heterodyne photon-echo spectra of Nile Blue, Chem. Phys. 341 (2007) 113
  D. Egorova, M. Gelin, W. Domcke
  
• Detection of electronic and vibrational coherences in molecular systems by 2D electronic photon echo spectroscopy, Chem. Phys. 347 (2008) 166
  D. Egorova
  
• Effects of intense femtosecond pumping on multilevel ultrafast dynamics with relaxation, J. Chem. Phys. 129 (2008) 214303
  D. Egorova, M. Gelin, M. Thoss, H. Wang, W. Domcke
  
• Efficient calculation of the polarization induced by N coherent laser pulses , J. Chem. Phys. 131 (2009) 194103
  M. Gelin, D. Egorova, W. Domcke
  
• Efficient Calculation of Time- and Frequency-Resolved Four-Wave-Mixing Signals, Acc. Chem. Res. 42 (2009) 1290
  M. Gelin, D. Egorova, W. Domcke
  
• Manipulating electronic couplings and nonadiabatic nuclear dynamics with strong laser pulses , J. Chem. Phys. 131 (2009) 124505
  M. Gelin, D. Egorova, W. Domcke
  
• Efficient and accurate simulations of two-dimensional electronic photon-echo signals: Illustration for a simple model of the Fenna-Matthews-Olson complex, J. Chem. Phys. 132 (2010) 014501
  L. Z. Sharp, D. Egorova, W. Domcke