Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27109, USA.
J Chem Phys. 2012 Jan 7;136(1):014509. doi: 10.1063/1.3673779.
The influence of a third molecule on the rate of resonance energy transfer is studied using diagrammatic perturbation theory within the framework of molecular quantum electrodynamics. Two distinct mechanisms are identified. One corresponds to direct transfer between donor and acceptor while the other involves relay of energy by the third species. Fermi Golden rule transition rates valid for all separation distances beyond wave function overlap are evaluated for these two processes as well as for the interference term between direct and indirect exchange, thereby extending previous work which was limited to the near-zone only. Short- and long-range limits are also obtained in each case. It is found that in the near-zone the indirect rate contribution exhibits inverse sixth power dependence on relative distances of emitter and absorber relative to the third body, in contrast to its far-zone counterpart, which exhibits inverse square behavior. The interference term, however, displays inverse cubic dependence on all three distance vectors at short-range and inverse behavior in the far-zone. Interestingly, for a collinear arrangement of the three molecules in the near-zone, the interference term is negative, reducing the overall rate of energy transfer. The results obtained are interpreted in terms of microscopic and macroscopic pictures of transfer occurring within a surrounding medium.
利用分子量子电动力学框架中的图式微扰理论研究了第三个分子对共振能量转移速率的影响。确定了两种不同的机制。一种对应于供体和受体之间的直接转移，而另一种则涉及第三种物质的能量中继。对于这两种过程以及直接和间接交换之间的干涉项，评估了适用于所有距离远大于波函数重叠的费米黄金规则跃迁率，从而扩展了先前仅限于近区的工作。在每种情况下，还获得了短程和长程极限。结果发现，在近区，间接速率贡献表现出与第三个物体的发射体和吸收体相对距离的六次方反比依赖性，而其远区对应物则表现出二次方行为。然而，在短程中，干涉项对所有三个距离向量都表现出立方反比依赖性，而在远区则表现出逆行为。有趣的是，对于三个分子在近区的共线排列，干涉项为负，降低了能量转移的总速率。根据在周围介质中发生的转移的微观和宏观图像解释了所得到的结果。
