Resonant radiative transfer

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... 

Forster (1968) points out that R0 is independent of donor radiative lifetime it only depends on the quantum efficiency of its emission. Thus, transfer from the donor triplet state is not forbidden. The slow rate of transfer is partially offset by its long lifetime. The importance of Eq. (4.4) is that it allows calculation in terms of experimentally measured quantities. For a large class of donor-acceptor pairs in inert solvents, Forster reports Rg values in the range 50-100 A. On the other hand, for scintillators such as PPO (diphenyl-2,5-oxazole), pT (p-terphenyl), and DPH (diphenyl hexatriene) in the solvents benzene, toluene, and p-xylene, Voltz et al. (1966) have reported Rg values in the range 15-20 A. Whatever the value of R0 is, it is clear that a moderate red shift of the acceptor spectrum with respect to that of the donor is favorable for resonant energy transfer. 

Lakowicz JR, Shen Y, D Auria S, Malicka J, Fang J, Gryczynski Z, Gryczynski I (2002) Radiative decay engineering 2. Effects of silver island films on fluorescence intensity, lifetimes, and resonance energy transfer. Anal Biochem 301 261-277... 

The first term is due to spontaneous radiative relaxation and nonradiative phonon relaxation as described in eq. (13), where / , is the probability of ion i in the excited state. The second term is due to energy transfer induced by ion-ion interaction, where W es and W A are rates of resonant and phonon-assistant energy transfer, which depend on distance between donor and acceptor RtJ. For resonant energy transfer... 

Like FRET, bioluminescence resonance energy transfer (BRET) is based on non-radiative energy transfer between a donor and an acceptor. However, in BRET, the donor is a luminescent molecule, excited by the enzyme Renilla Luciferase (Rluc), and not a fluorescent molecule. The BRET acceptor can be a fluorescent protein like green fluorescent protein (GFP) or YFR If the enzyme and the fluorescent protein are in close proximity (d < 10 nm), an energy transfer will occur between the Rluc substrate (coelanterazine) and the fluorescent protein, leading to emission from the later. 

Several other studies (150-153) reported that metal surfaces were able to either enhance or suppress the radiative decay rates of fluorophores. Furthermore, an increase in the extent of resonance energy transfer was also observed. These effects might be due to the interactions of excited-state fluorophores with SPs, which in turn produce constructive effects on the fluorophore. The effects of metallic surfaces include fluorophore quenching at short distances ( 0-5 nm), spatial variation of the incident light field (-0-15 nm), and changes in the radiative decay rates (-0-20 nm) (64). The term of metal-enhanced fluorescence could be referred to the appplication of fluorophore and metal interactions in biomedical diagnosis (64). 

Lakowicz, J. R., Shen, Y., D Auria, S., Malicka, J., Fang, J., Gryczynski, Z., and Gryc nski, I. (2002). Radiative Decay Engineering 2. Effects of Silver Island Films on Fluorescence Intensity, Lifetimes, and Resonance Energy Transfer. i4 a/. Biochem. 301 261-277. 

It is possible that surface enhancement effects, similar to the observations made earlier in metal-fluorophore systems [11, 83-85] may occur. Metal surfaces are known to have effects on fluorophores such as increasing or decreasing rates of radiative decay or resonance energy transfer. A similar effect may take place in ZnO nanomaterial platforms. However, decay lengths of fluorescence enhancement observed in the semiconducting ZnO NRs are not commensurate with the length scale seen on metals such as Au or Ag. For effective metal enhanced fluorescence, fluorophores should be placed approximately between 5-20 nm away from the metal surface. However, fluorescence enhancement effect on ZnO NRs is observed even when fluorophores are located well beyond 20 nm away from the NR surface. At the same time, no quenching effec en when they are placed directly onto ZnO NR surfaces. In addition, there overlap between the absorption and emission... 

Cardullo RA, Agrawal S, Flores C, Zamecnik PC, Wolf DE. Detection of nucleic acid hybridization by non-radiative fluorescence resonance energy transfer. Proc. Natl. Acad. Sci. U.S.A. 36. 1988 85 8790-8794. 

Since the Planckian source is a slowly-varying function of frequency, the sharp atmospheric absorption features in the observed data reveal information about the concentration of the absorbers. An iterative method based on the on-resonance off-resonance ratio of intensities at many absorption features was used to compute the concentration of atmospheric H2O, CO2, N2O, and CH4. This method does not require a model for the source intensity term and only assumes that its spectral variation with frequency is slow relative to most atmospheric absorption features. Accurate meteorological data was not available for the field test however, reasonable agreement was found between the calculated H2O concentration and that reported by the nearest weather station. Experimental CO2, N2O and CH4 concentrations were not available, but calculated values were consistent with historical averages. Atmospheric transmission modeling was performed using the Line-by-Line Radiative-Transfer-Model. ... 

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