Excitation energy transfer electronic

4 Electronic Excitation Energy Transfer - Studies dealing exclusively with energy transfer, theoretical or experimental, in homogeneous systems are very few in the year under review. Nevertheless some very seminal investigations have been made. 

The diffusion equation for long-range energy transfer by the dipole-dipole interaction mechanism which is accompanied by material diffusion has been solved numerically . The theory of enhanced energy transfer between molecules embedded in spherical dielectric particles has been developed for application to dipole-dipole energy transfer taking place between molecules embedded in aerosol droplets. The experimental systems studied involved the use of the dyes coumarin as donor and rhodamine 6G as acceptor. 

The nature of energy transport and percolation has been examined in mixed molecular crystals which are regarded as fractal structures S0. Strong guest host interaction produces induced energy funnels which are found to mask the fractal nature of the 

The relationship between excitation transport and fluorescence depolarization in two and three dimensional disordered systems has been discussed by Anfinrud and Struve . In the usual discussion of excitation transport by dipole-interaction it is conventional to assume that excitation is completely depolarized after a single hop. This supposition has been critically examined and a theory formulated suitable for application to Langmuir Blodgett films and absorbed species. 

A comparison of DODCI fluorescence depolarization in glycerol and ethylene glycol shows the effect of a orientational correlation on excitation transfer effect of rotational diffusion on 

4 Electronic Excitation Energy Transfer. - The number of papers dealing with theory and simple molecules appear to have declined over recent years. An exception to this statement involves biological systems and it is in biochemistry that most significant recent work on electronic excitation energy transfer has been done. Some recent examples will be mentioned in a later section of this review. 

Markoffian theories for luminescence of solids. For fluid systems a kinetic theory of excitation transfer between donor and acceptors, where reaction probability is modulated by translational diffusions, has been submitted to numerical analysis.  

An experimental investigation has been made of energy transfer 

Intramolecular electronic energy transfer in bichromophoric molecules consisting of two coumarins linked by a variable number 

2ljA Electronic Excitation Energy Transfer - Andrews has put 

Evesque on energy migration in fractal spaces such as those found in polymers and similarly organized systems. 

A number of papers deal with other more specific aspects of the theory of energy transfer. These include the long-time depolarization decay due to excitation transport, enhancement of energy transfer between donor and acceptor molecules near a long metallic wire or dielectric fibre in which guided modes are 

A particularly useful paper by Wagner and Ware applies the maximum entropy method for the recovery of fluorescence lifetime distributions to Forster transfer in rigid and viscous media. As shown by treatment of specific examples it is evident that this constitutes a powerful treatment for determining the distribution of rate constants in this type of system. 

A generalized model has been given for radiationless energy 

Radiative transfer is an unfortunate complication in many electronic energy transfer experiments and it is difficult either to eliminate or make satisfactory allowance for this effect. Martinho and d Olveira have studied in detail the influence of radiative transport on observations of electronic excitation energy transfer. In particular they have analyzed the effects of radiative transport on measured fluorescence decay curves for concentrated solutions. An experimental study of the influence of radiative transport on energy transfer from excited fluorene to pyrene it occurs n-hexane relates closely with this work . Kawski et have 

Nonradiative energy transfer with the simultaneous involvement of different mechanisms has been modelled by Rotman for solid state systems. Although his treatment is particularly directed towards inorganic systems it is generally relevant to organic systems also. The complex kinetics of sequential energy processes involving four species each with a dependence of rate coefficients has also been analyzed.  

Simulated coherent energy transfer in a hydrogen bonded amide chain arising from Fermi resonance has been modelled by Clarke and Collins . This interesting study is related to the Davydov soliton model which has been proposed for explaining energy transport in proteins. The role of similar nonlinear effects in simple organised chemical systems has yet to be established. 

Frequency domain fluorometry has been used to study end to end diffusion of flexible bichromophoric molecules by intramolecular energy transfer o - .  

A particularly interesting paper deals with chiral discrimination in electronic energy transfer processes between dissymmetric metal complexes in solution . Time resolved luminescence measurements show that enantioselective excited state quenching occurs. 

---

Agranovioh V M and Galanin M D 1982 Electronic Excitation Energy Transfer in Condensed Maffer (Amsterdam Elsevier/North-Flolland)... 

Gulis IM, Komiak AI, Tomin VI (1978) The electronic excitation energy transfer at conditions of dye spectra inhomogeneous broadening. Izv Akad Nauk SSSR, ser fiz 42 307-312... 

Agranovich, V. M. and Galanin, M. D. (1982). Electronic Excitation Energy Transfer in Condensed Matter. North-Holland Publishing Company, Amsterdam. 

In the following scheme the difference between intra- and inter-molecular electronic excitation energy transfer is summarized (as formulated in 2>) ... 

Sukhan has used PTAB cationic micelles to enhance the CL reaction of 4-diethylaminophthalohydrazide with oxygen and Co(II) in the presence of fluorescein as sensitizer [48], This enhancement is mainly due to electron-excited energy transfer from the donor (4-diethylaminophthalohydrazide) to the acceptor (fluorescein). The addition of fluorescein combined with the presence of PTAB reduces the detection limit of Co(II) by a factor of 6. The method was successfully applied in the determination of Co in tap water samples. 

V. M. Agranovich and M. D. Galanin, The Electronic Excitation Energy Transfer in Condensed Media, Nauka, Moscow (1978). 

Another theoretical method widely applied to describing the kinetics of electron tunneling reactions is based on the employment of the so-called conditional concentrations. This method was first suggested by Galanin [5] in the theory of electron excitation energy transfer and by Antonov-Roma-novskii in the theory of particle recombination [17]. 

---