Forster-Dexter theory

In the original Forster-Dexter theory [79-81] the superexchange terms in 7), have been ignored, that is, 7, - = //) . We shall present the derivation of their theory in our framework. Consider the energy transfer... 

The next two chapters are devoted to ultrafast radiationless transitions. In Chapter 5, the generalized linear response theory is used to treat the non-equilibrium dynamics of molecular systems. This method, based on the density matrix method, can also be used to calculate the transient spectroscopic signals that are often monitored experimentally. As an application of the method, the authors present the study of the interfadal photo-induced electron transfer in dye-sensitized solar cell as observed by transient absorption spectroscopy. Chapter 6 uses the density matrix method to discuss important processes that occur in the bacterial photosynthetic reaction center, which has congested electronic structure within 200-1500cm 1 and weak interactions between these electronic states. Therefore, this biological system is an ideal system to examine theoretical models (memory effect, coherence effect, vibrational relaxation, etc.) and techniques (generalized linear response theory, Forster-Dexter theory, Marcus theory, internal conversion theory, etc.) for treating ultrafast radiationless transition phenomena. 

Strome and Klier 107,108) applied the Forster-Dexter theory of resonance energy transfer to explain these experimental observations, i,e., the energy transfer from the excited state of the Cu species to the coexistent... 

The results of the luminescence decay for 8-10 were analysed in terms of the Forster-Dexter theory for multi-polar interaction between the donor (D) and the acceptor (A) (Yamase and Naruke, 1999). Since both the Tb-Tb transfer and the back transfer from Eu to Tb at 4.2 K are negligible, the intensity [7(f)] of the Tb emission after pulsed excitation can be described by the Inokuti-Hirayama... 

Olaya-Castro A, Scholes GD (2011) Energy transfer from Forster-Dexter theory to quantum coherent light-harvesting. Int Rev Phys Chem 30 49-77... 

From Table 13.11, the variation of the lifetimes and fluorescence quantum yields in the series of compounds shows the clear increase of homo-chromophore interactions in the excited states when the distance between the chromophores diminishes. The rate and efficiency of the energy transfer in hetero-dimers does not seem to be metal dependent. The distance dependence of the energy transfer rate has been analyzed using Forster and Dexter theories. Harvey and Guilard have established that in 135-Zn-H2 and 136-Zn-H2, energy transfer is dominated by a Forster mechanism, while in the case of hetero-dimers 137, 138, and 139, it proceeds mainly via a Dexter mechanism. The critical distance at which the Dexter mechanism becomes inoperative is estimated between 5 and 6 By analogy with what has been discussed earlier in the case of linearly arranged covalent dimers, it should be noted that for compounds 135-139, no electron density should be present on the meso carbons involved in the covalent connection to the spacer. 

The Forster [62,63] and Dexter [64] theory in photo-induced energy transfer is discussed. For the singlet-singlet energy transfer [65,66]... 

In contrast, EET has been historically modelled in terms of two main schemes the Forster transfer [15], a resonant dipole-dipole interaction, and the Dexter transfer [16], based on wavefunction overlap. The effects of the environment where early recognized by Forster in its unified theory of EET, where the Coulomb interaction between donor and acceptor transition dipoles is screened by the presence of the environment (represented as a dielectric) through a screening factor l/n2, where n is the solvent refractive index. This description is clearly an approximation of the global effects induced by a polarizable environment on EET. In fact, the presence of a dielectric environment not only screens the Coulomb interactions as formulated by Forster but also affects all the electronic properties of the interacting donor and acceptor [17],... 

Electrochemical and photochemical processes are the most convenient inputs and outputs for interfacial supramolecular assemblies in terms of flexibility, speed and ease of detection. This chapter provides the theoretical background for understanding electrochemical and optically driven processes, both within supramolecular assemblies and at the ISA interface. The most important theories of electron and energy transfer, including the Marcus, Forster and Dexter models, are described. Moreover, the distance dependence of electron and energy transfer are considered and proton transfer, as well as photoisomerization, are discussed. 

Luminescence of rare earth ions can be understood, based on transitions between (almost) atomic eigenstates of the system [5.220, 5.221]. Forster and Dexter first described energy transfer between localized centers in luminescent material [5.222-5.224]. Besides orbital theory, semiconductor theory has also contributed to the understanding of radiative transitions Both band-to-band transitions and transitions involving localized donor and/or acceptor states fit within this framework. Nevertheless, there are also still open questions concerning the theoretical aspects. 

Details on the mechanisms and theories of excitation energy transfer via dipole-dipole interaction (FRET Forster resonance energy transfer) and via exchange interaction (Dexter s mechanism) can be found in B. Valeur, Molecular Fluorescence. Principles and Applications, Wiley-VCH, Weinheim, 2002, chap. 4 and 9. 

The theory of resonant nonradiative ED-ED ET was formulated by Forster, and extended by Dexter to include other interaction mechanisms. From the Fermi Golden Rule, the ET rate, WDA, between an excited donor (D ) and an acceptor (A) in nondegenerate states is proportional to the square of the interaction matrix element, /, [358] ... 

Here we present a brief review of the physical principles underlying fluorescence energy transfer. The theory was developed primarily by Fdrster and extended by Dexter.Forster did some early experimental studies, and Stryer and Haugland convincingly showed that fluorescence energy transfer could be used as a molecular ruler to measure distances. Emphasis is on developing an intuitive feel for the important relevant parameters. Both a classical and a quantum mechanical approach are given. 

The theory of Forster treats only allowed transitions. Dexter has extended this theory to include a transfer mechaitism by means of forbidden transitions. ... 

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