Phonon-mediated excitation energy transfer in a detuned multi-sites system

Abstract

Based on a ring-shaped arrangement of interacting two-level systems, we show the important role of the phonon-mediated quantum interference in excitation energy transfer, mimicking light-harvesting antenna in natural photosynthetic systems. The pigments in a ring-shaped photosynthetic system interact with the high-energy intramolecular vibrational mode, which arises from the vibrational motion of the scaffold of the system, with different coupling phases according to the position of each pigment respect to the vibrational motion. By investigating the model systems, we demonstrate that in the presence of large detuning between donor pigments and acceptor pigments, the efficiency of excitation transfer depends directly on the relative coupling phase between two adjacent pigments. Our model system, containing more pigments, shows a better robustness of the phonon-mediated excitation energy transfer. The present results are not only helpful in understanding natural photosynthesis, but also offer an optimal design principle for artificial photosynthesis.

Vibronic Quantum Beating between Electronic Excited States in a Heterodimer

“…Since NACT12 values are larger at 300 K than 10 K, this effect allows a more effective resynchronization of EHR-NEXMD trajectories at higher temperature, that is translated to the more efficient and cohesive electronic population transfer shown in Figure 2. As it has been pointed out by numerous previous works using model Hamiltonians, 25,26,[35][36][37][38][39][40] coherent exciton-vibrational dynamics, that emerges from nonadiabatic transitions between excited states, can persists over long timescales at room temperature. [4][5][6][7] Non-adiabatic transitions between excited states funnel the energy through specific vibrational motions.…”

“…As it has been pointed out by numerous previous works using model Hamiltonians, ,,− coherent exciton–vibrational dynamics, that emerges from nonadiabatic transitions between excited states, can persists over long time scales at room temperature. − Nonadiabatic transitions between excited states funnel the energy through specific vibrational motions. Consequently, the nonequilibrium dynamics of such selected vibrations modulates the beating of excitonic populations even at ambient conditions.…”

“…34 That is, the non-equilibrium dynamics of such selected vibrations can be manifested itself in ultrafast beating of excitonic populations. 25,26,[35][36][37][38][39][40] The photoexcitation and subsequent electronic and vibrational energy redistribution and relaxation in multichromophoric molecular systems involve processes like internal conversion, and transient exciton localization/delocalization, and couplings among the multiple electronic and vibrational excited states that actively participate in the process. In order to achieve an atomistic description of such processes, molecular dynamics simulations involving several coupled electronic excited states and vibrational degrees of freedom are required.…”

“…Persistent quantum coherence, discovered in natural and artificial ,− multichromophoric light harvesting systems was originally attributed to solely electronic degrees of freedom, and later has been associated with the complex interactions between vibrational and electronic (vibronic) degrees of freedom during coherent exciton–vibrational dynamics. , A common scenario for energy transfer in multichromophores involves nonadiabatic (i.e., beyond Born–Oppenheimer approximation) evolution of electronic populations involving multiple electronic states. , Nowadays, strong evidence support the idea that coherent exciton–vibrational dynamics, that emerge from nonadiabatic transitions between excited states, can persists over long (frequently picosecond) time scales at room temperature. − Nonadiabatic transitions between excited states funnel the energy transfer through specific classical vibrational motions that modulate the wave-like localized–delocalized motion of the electronic wave function . That is, the nonequilibrium dynamics of such selected vibrations can be manifested itself in ultrafast beating of excitonic populations. ,,− …”

Cooperation between Excitation Energy Transfer and Antisynchronously Coupled Vibrations

“…Recently, exciton–phonon coupling has been widely studied toward exploring efficient energy transfer pathways. − In particular, the effect of discrete underdamped vibrations has been drawing many researchers’ attention. − When the energy flows from a donor to an acceptor, a vibration that is resonant with the donor–acceptor energy gap can enhance energy transfers by fulfilling the energy conservation. − The vibration not only contributes as a simple energy ladder but also affects the transfer rather intricately by inducing vibronic mixing between electronic states. , Indeed, the importance of such vibrations has been demonstrated with various systems. − …”