Electronic-Vibrational Resonance Does Not Significantly Alter Steady-State Transport in Natural Light-Harvesting...

Area of Science:

• Quantum dynamics
• Photosynthetic energy transfer
• Spectroscopy

Background:

• Quantum coherence, observed via oscillations in time-dependent two-dimensional electronic spectra, is linked to electronic-vibrational resonant interactions in light-harvesting systems.
• Natural light-harvesting processes occur in a non-equilibrium steady-state, questioning the direct relevance of observed quantum coherence to natural conditions.

Purpose of the Study:

• To investigate the role of intramolecular vibrations in the non-equilibrium steady-state of photosynthetic dimers under natural incoherent light excitation.
• To assess the impact of electronic-vibrational resonance on energy transport efficiency in photosynthetic systems.

Main Methods:

• Analysis of the PEB dimer within the cryptophyte algae PE545 antenna protein.
• Modeling and simulation of energy transport dynamics under non-equilibrium steady-state conditions.
• Comparison of resonant versus non-resonant vibrational interactions.

Main Results:

• Vibrations resonant with exciton state energy differences only marginally increased quantum yield.
• Resonant vibrations showed a minor increase in the imaginary part of intersite coherence, crucial for transport.
• Non-resonant vibrations had a comparable or greater effect on energy transport metrics.

Conclusions:

• Electronic-vibrational resonance interactions do not significantly enhance energy transport in photosynthetic dimers under natural incoherent light.
• The findings suggest that quantum coherence effects observed in laboratory settings may not directly translate to improved efficiency in natural light-harvesting scenarios.