Long-range resonance transfer

Forster (1959) classifies the qualitative features based on which one can distinguish the various modes of energy transfer. Mainly, only collisional transfer depends on solvent viscosity (vide infra), whereas complexing between the donor and acceptor changes the absorption spectrum. On the other hand, the sensitizer lifetime decreases for the long-range resonant transfer process, whereas it should be unchanged for the trivial process. 

Several theories have been developed to explain how energy absorbed by one molecule is transferred to a second acceptor molecule of the same or a different species. At first sight exciton theory,20 66 which accounts for excitation transfer in molecular aggregates or crystals and the Davydov splitting effects connected with it, appears to bear little relationship to the treatment of long-range resonance transfer as developed, for example, by Forster.81-32 However, these theories can be shown to arise from the same general considerations treated at different well-defined mathematical limits.33-79... 

This change is attributed to interparticle dipolar interactions [771], Bawendi and coworkers [772] have studied the changes in ensembles of CdSe nanocrystals of different diameters and obtained evidence for long-range resonance transfer of electronic excitation from smaller to bigger nanocrystals due to dipolar interactions. 

Kagan, C. R., Murray, C. B., Bawendi, M. G. (1996). Long-range resonance transfer of electronic excitations in close-packed CdSe quantum-dot solids. Physical Review B, 54, 8633-8643. 

All of the examples of singlet energy transfer we have considered take place via the long-range resonance mechanism. When the oscillator strength of the acceptor is very small (for example, n-> n transitions) so that the Fdrster critical distance R0 approaches or is less than the collision diameter of the donor-acceptor pair, then all evidence indicates that the transfer takes place at a diffusion-controlled rate. Consequently, the transfer mechanism should involve exchange as well as Coulomb interaction. Good examples of this type of transfer have been provided by Dubois and co-workers.(47-49)... 

Scholes, G. D. 2003. Long-range resonance energy transfer in molecular systems. Annu. Rev. Phys. Chem. 54 57-87. 

The possibility that there might be long-range electron transfer between redox-active centers in enzymes was first suspected by biochemists working on the mechanism of action of metalloenzymes such as xanthine oxidase which contain more than one metal-based redox center. In these enzymes electron transfer frequently proceeds rapidly but early spectroscopic measurements, notably those by electron paramagnetic resonance, failed to provide any indication that these centers were close to one another. 

Meldal et al. developed a novel protease assay based on the long-range resonance energy transfer (FRET) [25] fluorescence quenched (EQ) pair 3-nitrotyro-sine/2-aminobenzoic acid. This served to characterize enzyme specificity by direct visual inspection of the resin beads (33). 

The non-adiabatic long-range electron transfer (LRET) has been proven to be one of the key stages of many processes in enzymes, proteins and model systems. Therefore, theoretical calculation and experimental determination of the resonance integral (V) and its dependence on the distance between donor and acceptor centers appears to be a fundamental problem. 

Energy transfer from COj and NjO (001) to the molecules CH D4 where =0-4 have been measured and discussed. The deactivation of CO2 ((X)l) or N2O (001) appears to correlate well with the number of stretching modes in the 2200 cm region, which in turn correlates with the number of deuterium atoms in the colHsion partner. This correlation is discussed with regard to near-resonant long-range energy-transfer theory... 

Let us first consider the case of the dynamic quenching, which means that the interaction between the fluorophore and the quencher occurs in the excited state of the fluorophore, F, either as a collision or a long-range resonance energy transfer between F and Q, both leading to nonradiative deactivation of F. The excited-state lifetime t can be expressed by the sum of the rate constants of individual deactivation processes ... 

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