info:eu-repo/semantics/article
High magnetic field detunes vibronic resonances in photosynthetic light harvesting
Fecha
2018-09Registro en:
Maiuri, Margherita; Oviedo, María Belén; Dean, Jacob C.; Bishop, Michael; Kudisch, Bryan; et al.; High magnetic field detunes vibronic resonances in photosynthetic light harvesting; American Chemical Society; Journal of Physical Chemistry Letters; 9; 18; 9-2018; 5548-5554
1948-7185
CONICET Digital
CONICET
Autor
Maiuri, Margherita
Oviedo, María Belén
Dean, Jacob C.
Bishop, Michael
Kudisch, Bryan
Toa, Zi S. D.
Wong, Bryan M.
McGill, Stephen A.
Scholes, Gregory D.
Resumen
The origin and role of oscillatory features detected in recent femtosecond spectroscopy experiments of photosynthetic complexes remain elusive. A key hypothesis underneath of these observations relies on electronic-vibrational resonance, where vibrational levels of an acceptor chromophore match the donor-acceptor electronic gap, accelerating the downhill energy transfer. Here we identify and detune such vibronic resonances using a high magnetic field that exclusively shifts molecular exciton states. We implemented ultrafast pump-probe spectroscopy into a specialized 25 T magnetic field facility and studied the light-harvesting complex PC645 from a cryptophyte algae where strongly coupled chromophores form molecular exciton states. We detected a change in high-frequency coherent oscillations when the field was engaged. Quantum chemical calculations coupled with a vibronic model explain the experiment as a magnetic field-induced shift of the exciton states, which in turn affects the electronic-vibrational resonance between pigments within the protein. Our results demonstrate the delicate sensitivity of interpigment coherent oscillations of vibronic origin to electronic-vibrational resonance interactions in light-harvesting complexes.