Mediation of resonance energy transfer by a third molecule.
Mediation of resonance energy transfer by a third molecule.
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通过第三个分子介导共振能量转移。
作者：
A. Salam
在分子量子电动力学的框架内，利用图解微扰理论研究了第三分子对共振能量转移速率的影响。确定了两种不同的机制。一个对应于供体和受体之间的直接转移，而另一个涉及第三物种的能量中继。费米黄金法则过渡率有效的波函数重叠以外的所有分离距离进行评估，这两个过程，以及直接和间接的交流之间的干扰项，从而扩展以前的工作仅限于近区。在每种情况下，也获得了短期和长期的限制。结果发现，在近区的间接率的贡献表现出反六次幂的发射体和吸收体相对于第三体的相对距离的依赖关系，相反，其远区对应，表现出平方反比的行为。然而，干扰项在近距离显示出对所有三个距离矢量的反三次依赖性，而在远区显示出相反的行为。有趣的是，对于近区中三个分子的共线排列，干涉项是负的，降低了能量转移的总速率。所获得的结果进行解释的微观和宏观图片的传输发生在周围介质中。
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.