Resonance transfer, Forster

The most important mechanism for singlet energy transfer is the Forster 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. 

The theory of resonance transfer of electronic excitation energy between donor and acceptor molecules of suitable spectroscopic properties was first presented by Forster.(7) According to this theory, the rate constant for singlet energy transfer from an excited donor to a chromophore acceptor which may or may not be fluorescent is proportional to r 6, where r is the distance... 

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... 

The energy transfer process in the antenna system is generally considered to take place according to a resonance transfer mechanism first proposed by Forster (see below). The antenna system increases the effective cross-section of photon absorption by increasing the number of pigments associated... 

FRET Fluorescence resonance energy transfer Forster resonance energy transfer... 

Q.27.4 A solvent with an ionic strength of 0.15 alters the Ro of fluorochrome pair above to 15 A because of the effect of the local electric field from the ions on the resonance transfer. You reconstitute your pore assembly and notice that when the conductivity of the membrane increases the Forster efficiency drops to 25%. Explain this effect and describe the state of the environment in the pore in the conducting and non-conducting state. 

Fig. 20. Simplified scheme of resonant energy Forster energy transfer between a donor (D) and an acceptor (A). Right side shows energy transfer to a trap which is lower in its singlet...

Keywords Oxalate networks [Cr(ox)3]3- [Cr(bpy)3]3+ 2E state Resonant energy transfer Phonon-assisted energy transfer Forster transfer Exchange interaction... 

When the first formed excited state is quenched by a fluorescent molecule present in solution, with radiation from the acceptor, sensitised chemiluminescence results. This form of emission is most easily seen when the transfer of energy takes place between singlet states (i. e. by the resonance or Forster mechanism... 

Deniz A A, Dahan M, Grunwell J R, Ha T, Faulhaber A E, Chemla D S, Weiss S and Schultz P G 1999 Single-pair fluorescence resonance energy transfer on freely diffusing molecules observation of Forster distance dependence and subpopulations Proc. Natl Acad. Sc/. USA 96 3670-5... 

Fig. 4.1.17 Graphic illustration of Forster-type resonance energy transfer from aequorin to Aequorea GFP. In the vessel at left, a solution contains the molecules of aequorin and GFP randomly distributed in a low ionic strength buffer. The vessel at right contains a solution identical with the left, except that it contains some particles of DEAE cellulose. In the solution at right, the molecules of aequorin and GFP are coadsorbed on the surface of DEAE particles. Upon an addition of Ca2+, the solution at left emits blue light from aequorin (Xmax 465 nm), and the solution at right emits green light from GFP (Xmax 509 nm).

The occurrence of energy transfer requires electronic interactions and therefore its rate decreases with increasing distance. Depending on the interaction mechanism, the distance dependence may follow a 1/r (resonance (Forster) mechanism) or e (exchange (Dexter) mechanisms) [ 1 ]. In both cases, energy transfer is favored by overlap between the emission spectrum of the donor and the absorption spectrum of the acceptor. 

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