Radiationless transfer of energy

Figure 4.2. Energy levels involved in the sensitized fluorescence of potassium and rubidium, induced in collisions between excited potassium and ground-state rubidium atoms. The s coefficients refer to optical excitation, r 1 to radiative decay, and Z to radiationless transfer of energy by inelastic collisions.

Fig.1 Schematic of the FRET process. Excitation of the fluorescent donor is followed by radiationless transfer of energy to the acceptor chromophore, returning the donor to the ground state. FRET is then usually, although not always, manifested by subsequent fluorescence of the acceptor...

A may also return to the ground state via a radiationless transition, most commonly by collisional transfer of energy to a solvent molecule. 

M. Kupryszewska, I. Gryczynski, and A. Kawski, Intramolecular donor-acceptor separations in methionine- and leucine-enkephalin estimated by long-range radiationless transfer of singlet excitation energy, Photochem. Photobiol. 36, 499-502 (1982). 

An exchange mechanism has also been considered for the transfer of energy. The rate constant of the exchange mechanism (Equation 6.88) resembles the rate constant of a radiationless relaxation in the activated limit showed in Equation 6.72. 

Ermolaev, V. L., Bodunov, E. N., Sveshnikova, E. B., and Shakhverdov, T. A. (1977) Radiationless Transfer of Electronic Excitation Energy, Nauka. Leningrad. 

All these results indicate that, with titanium-silicon binary oxides having low titanium contents the Ti ions are enriched near the surface regions, separated from each other, and present as tetrahedral species in the Si02 carrier matrices. In such species, the radiationless transfer of photon energy absorbed by Ti02 is suppressed because of the low coordination of the ions. As a result, the formation of the (electron-hole) ion pairs, i.e., the excited state of (Ti +- 0 ) complexes, is facihtated (200, 201). 

Although the number of EFS traps will be an important factor governing the observed fluorescence, a second factor of equal or sometimes greater importance is the phenomenon of electronic excitation transport (EET) [51, 58-61]. This involves the radiationless transfer of excitation energy, in the singlet state for compounds in this work, from one aromatic chromophore to another. This process may be viewed as a random walk with the rate of transfer between randomly oriented absorption and emission dipoles being given at each step by... 

Juzeliunas G and Andrews D L 1999 Unified theory of radiative and radiationless energy transfer Resonance Energy Transfer ed D L Andrews and A A Demidov (New York Wiley) pp 65-107... 

The original stabilizer (HBC) was modified as the rapid radiationless deactivation of the stabilizer is (at least partly) due to the intramolecular hydrogen bond, the H-atom was substituted by a methyl group (MBC). This "probe molecule" showed fluorescence and phosphorescence and enabled us to demonstrate the energy transfer to the stabilizer, simply by studying its sensitized luminescence. 

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