I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstraße 9, 20355, Hamburg, Germany.
Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany.
Photosynth Res. 2020 May;144(2):137-145. doi: 10.1007/s11120-020-00742-x. Epub 2020 Apr 18.
We study the impact of underdamped intramolecular vibrational modes on the efficiency of the excitation energy transfer in a dimer in which each state is coupled to its own underdamped vibrational mode and, in addition, to a continuous background of environmental modes. For this, we use the numerically exact hierarchy equation of motion approach. We determine the quantum yield and the transfer time in dependence of the vibronic coupling strength, and in dependence of the damping of the incoherent background. Moreover, we tune the vibrational frequencies out of resonance with the excitonic energy gap. We show that the quantum yield is enhanced by up to 10% when the vibrational frequency of the donor is larger than at the acceptor. The vibronic energy eigenstates of the acceptor acquire then an increased density of states, which leads to a higher occupation probability of the acceptor in thermal equilibrium. We can conclude that an underdamped vibrational mode which is weakly coupled to the dimer fuels a faster transfer of excitation energy, illustrating that long-lived vibrations can, in principle, enhance energy transfer, without involving long-lived electronic coherence.
我们研究了欠阻尼分子内振动模式对二聚体中激发能量转移效率的影响，其中每个状态都与其自身的欠阻尼振动模式以及连续的环境模式耦合。为此，我们使用数值精确的运动方程层次结构方法。我们确定了量子产率和转移时间与振子耦合强度的关系，以及与非相干背景阻尼的关系。此外，我们将振动频率调谐到与激子能隙失谐。结果表明，当供体的振动频率大于受体时，量子产率最高可提高 10%。此时，受体的振子能本征态具有更高的态密度，从而导致受体在热平衡时的占据概率更高。我们可以得出结论，与二聚体弱耦合的欠阻尼振动模式会促进激发能量更快地转移，这表明长寿命振动在不涉及长寿命电子相干的情况下，原则上可以增强能量转移。
