Photo-induced energy transfer

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

That is, is due to the Coulomb and exchange interactions. Ignoring the exchange interaction and carrying out the multi-pole expansion for the Coulomb interaction yield 

Here the dielectric constant e is introduced to take care of the medium effect if Rda is large. H is often rewritten as 

Neglecting the super-exchange contribution the thermal average rate constant for the singlet-singlet transfer can be expressed as 

for simplicity the dephasing constant jfu iv is ignored. Using the relations 

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The results presented in this section are very general and can be applied to IC, ISC, photo-induced energy transfer (EET) and photo-induced electron transfer (ET) [26,30-36],... 

Photo-Induced Electronic Transfer and Photo-Induced Energy Transfer. 199... 

In the previous sections, the expressions for non-adiabatic transitions have been obtained to the first-order approximations. To treat photo-induced energy transfer and photo-induced electronic transfer, to take into account the bridge effect between donor and accepter molecules, the higher order approximations need to be considered. In this case, instead of Eq. (40), the following equation is used ... 

A racemic, bichromophoric C70-pyrene conjugate showing intramolecular photo-induced energy transfer from the excited singlet state of the PAH to the fullerene has been reported by Daub and co-workers.383 Its chirality is based on the stereogenic center resulting from reduction of a fullerene-fused cyclohexanone, itself obtained by Diels-Alder addition of 2-[(trimethylsilyl)oxy]buta-1,3-diene to the C(l)-C(2) bond of C70 and subsequent hydrolysis of the formed silyl enol ether (cf. Section IV.C.l.d and Scheme 1.18). 

A similar photo-induced energy transfer was observed by Hupp and co-workers in a 4 -czsDPyP semi-zincated 2-1-2 metallacycle featuring ReCl(CO)3, rather than RuCl2(CO)2, corners [56]. 

Devices based on photo-induced energy transfer. Molecular wires can be... 

Electron impact mass spectrometry of the cyclobutanedione (24) gives rise to dimethylcarbene radical cation.35 Appearance energy measurements and ah initio calculations indicated that the radical cation lies 84 kJ mol 1 above the propene radical cation and is separated from it by a barrier of 35 kJ mol-1. Diarylcarbene radical cations have been generated by double flash photolysis of diaryldiazomethanes in the presence of a quinolinium salt (by photo-induced electron transfer followed by photo-initiated loss of N2).36 Absolute rate constants for reactions with alkenes showed the radicals to be highly electrophilic. In contrast to many other cation radicals, they also showed significant radicophihc properties. 

A transfer of the excitation energy from the donor to the acceptor will occur when an energy acceptor molecule is placed at the proximity of an excited energy donor molecule. After energy transfer, the donor relaxes to its ground state and the acceptor is promoted to one of its excited states. A photo-induced electron transfer can be initiated after photoexcitation when an excited single electron in the LUMO of the electron donor is transferred to a vacant molecular orbital (LUMO) of the acceptor. 

Photo-induced electron transfer represents one of the most basic photochemical reactions and at the same time it is the most attractive way to convert light energy or to store it for further applications. In Figure 14, one can see a... 

In many photo-related biosystems such as photo synthetic RCs and/or antenna complexes, photo-induced electronic transfer and photo-induced electronic energy transfer occur. In order to describe these transfer processes, the theoretical formulas for their rate constants are introduced within the BO approximation. 

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