ELFT HÍRADÓ

[bordacs.sandor AT wigner.bme.hu]

Kedves Kollégák,

Szeretném a figyelmükbe ajánlani az MTA-BME Magneto-optikai 
Spektroszkópia Lendület csoport következő szemináriumát.

Időpont: 2016. január 8. 14:15
Helyszín: BME, Budafoki út 8. F épület III. lh. Szemináriumi szoba

David Palecek
Department of Chemical Physics, Lund University, Sweden
Department Chemical Physics and Optics, Charles University in Prague

"Quantum Coherence for Light Harvesting"

Two-dimensional electronic spectroscopy has proven to be especially well 
suited for studying
coupled molecular systems, providing new insights into the population 
and coherence dynamics.
Multiple ultra short laser pulses are employed to extract maximum 
possible information about
the system in both time and energy [1]. Amplitude oscillations in the 2D 
spectra is a direct
evidence of the dynamically evolving superposition states. Interestingly 
enough, they were
initially interpreted as a purely electronic superposition with a 
conclusion that excitation
energy can be transferred coherently through the light-harvesting 
complexes. This finding
stimulated an immense scientific effort to understand the mechanisms of 
such wave-like energy
transfer [2]. In the case of photosynthetic reaction center, we 
identified a new photophysical
mechanism of the coherent dynamics; Energy Transfer Induced Coherence 
Shift (ETICS). In
ETICS mechanism, the initial excited state coherence is shifted to the 
ground state of the
donor upon energy transfer step without the loss of vibronically mixed 
character and phase
information. Yet it acquires the picosecond lifetime of the ground state 
vibrational coherence
[3]. Our results suggest that the hypothesis of the wave-like energy 
transfer has to be revisited.
References

[1] Brixner, T. et al. Phase-stabilized two-dimensional electronic 
spectroscopy. J. Chem. Phys.,
121(9):4221–4236, 2004.
[2] Engel, G. S. et al. Evidence for wavelike energy transfer through 
quantum coherence in
photosynthetic systems. Nature, 446(7137):782–786, April 2007.
[3] Paleˇcek, D. et al. Quantum coherence as a witness of vibronically 
hot energy transferin
bacterial reaction centre. In manuscript, 2016

Üdvözlettel,

Bordács Sándor

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