Excitons exciton fusion

Klymko, P. and Kopelman, R., Fractal reaction-kinetics Exciton fusion on clusters, Journal of Physical Chemistry, Vol. 87, No. 23, 1983,... 

The singlet-singlet collision process is often referred to as singlet exciton fusion. The end result of such a fusion reaction... 

This kinetic analysis of the singlet exciton fusion process is provided by the equation... 

The fusion of two triplets may give rise to autoionization as observed in the case of singlet exciton fusion (67)... 

Time dependent fluorescence depolarization is influenced by the exciton annihilation which occurs in confined molecular domains . Photoemission results from singlet exciton fusion as shown by the excitation intensity dependence which occurs in anthracene crystals. Reabsorption of excitonic luminescence is an effect which has been shown to occur in pyrene crystals. The dynamics of exciton trapping in p-methylnaphthalene doped naphthalene crystals involves phonon assisted detrapping of electronic energy. Ps time resolved spectroscopy was the experimental technique used in this work. 

Lately it was found, that the same mechanism is realized also in bacteria41 b. Exciton fusion processes observed by excitation of photosynthesis with very intensive ps- or ns-flashes41c,d practically do not occur under natural excitation conditions (s. Ref.41b ). 

It is a competing process to Si So emission and is partly responsible for the the low fluorescence quantum yield from crystalline tetracene. Fission is also a biex-citonic process, which, like triplet exciton fusion, can be modulated by an applied magnetic field with a similar dependence as shown in Fig. 6.24 for fusion (see also Fig. 6.26). The fluorescence intensity of tetracene is therefore magnetic-field dependent [51]. 

Klymko, P. W. Kopelman, R. Fractal reaction kinetics exciton fusion on clusters. I Phys. Chem. 1983, 87(23), 4565-4567. 

A semiquantitative model of the effects of L on Ip>F rid Ip was given by Webber and Swenberg (11). These authors analyzed the dependence of exciton annihilation on parameters such as lattice size, lattice dimensionality and the exciton fusion rate using a Pauli-Master equation. Their treatment is quite similar to the formalism of Paillotin et (12) used in modeling the fluorescence quantum yield decreases observed in photosynthetic membranes (13) with increasing excitation... 

In case of interaction between excitations, exciton-exciton annihilations (or fusion) are the most likely mechanisms to be employed for an energy density dependence of the transient decays. The dynamics is reflected in a Riccatti rate equation including simultaneous monomolecular and bimolecular processes,... 

Colliding triplet excitons are said to undergo triplet-triplet fusion. If they belong to the same species, the process is called homofusion. The collision of triplets belonging to different species is called heterofusion. The final products of the triplet-triplet interaction process are preceded by intermediate complex pair states ... 

Case I The triplet exciton concentration is too low to give rise to triplet-triplet fusion and the T2 terms in Eqs. (331) can be dropped. Then,... 

A triplet exciton annihilation mechanism has been proposed for charge generation in molecularly doped polymers initiated with very fast, high-intensity, excitation [25b,c]. In this mechanism it is proposed that both charge separation, associated with the Onsager model, and the fusion process are very strongly field-dependent. This model has not been invoked in recent years. 

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