Forster limit

Standards imposed to the industrial waste streams charged in heavy metals are more and more drastic in accordance with the updated knowledges of the toxicity of mercury, cadmium, lead, chromium... when they enter the human food chain after accumulating in plants and animals (Forster Wittmann, 1983). Nowadays, the use of biosorbents (Volesky, 1990) is more and more considered to complete conventional (physical and chemical) methods of removal that have shown their limits and/or are prohibitively expensive for metal concentrations typically below 100 mg.l-i. 

J. M., Forster, C., Gautier, J. C., Saudemon, P., Devoiselle, J. M., Wunderli-Allenspach, H., Potentiometric log P determination in the liposome/water system advantages and limitations, Pharm. 

Salt effects in polyelectrolyte block copolymer micelles are particularly pronounced because the polyelectrolyte chains are closely assembled in the micellar shell [217]. The situation is quite reminiscent of tethered polymer brushes, to which polyelectrolyte block copolymer micelles have been compared, as summarized in the review of Forster [15]. The analogy to polyelectrolyte brushes was investigated by Guenoun in the study of the behavior of a free-standing film drawn from a PtBS-PSSNa-solution [218] and by Hari-haran et al., who studied the absorbed layer thickness of PtBS-PSSNa block copolymers onto latex particles [219,220]. When the salt concentration exceeded a certain limit, a weak decrease in the layer thickness with increasing salt concentration was observed. Similar results have been obtained by Tauer et al. on electrosterically stabilized latex particles [221]. 

Deviations from the Forster decay (Eq. 9.29) arise from the geometrical restrictions. In the case of spheres, the restricted space results in a crossover from a three-dimensional Forster-type behavior to a time-independent limit. In an infinite cylinder, the cylindrical geometry leads to a crossover from a three-dimensional to a one-dimensional behavior. In both cases, the geometrical restriction induces a slower relaxation of the donor. 

Forster T, Roy D, Ghazal P (2003) Experiments using microarray technology limitations and standard operating procedures. J Endocrinol 178 195-204... 

The values of /labs were determined from the experimentally measured absorption anisotropy with Eq. 6. In viscous polyTHF, the rotational movement of dye molecules on a lOOps time scale is assumed to be negligible, and thus, does not reduce the limiting value of anisotropy. For the concentrated fluorene solutions (5 x 10 M, 1 mm cuvette), the anisotropy Tabs was not affected by FOrster depolarization mechanisms [13] due to the short time delay, tD, between probe and pump pulses when td/ti 1 [35]. 

Forster s cycle (50MI1) (method 1 in Table VIII, also known as the thermodynamic method ). This cycle is particularly important because it can be used even when the protolytic equilibrium is not reached in the excited state. On the other hand, it has two important limitations (i) the frequencies of the 0-0 transitions in absorption or emission are necessary and (ii) ionization entropy changes are assumed to be the same in the ground and in the excited states. The experimental difficulties involved in determining the 0-0 transition frequencies have led to the use of the frequencies of the absorption maxima (procedure a), emission maxima (procedure b), or the average therefrom (procedure c). 

Holger Herwig, Total rhetoric, limited war Germany s U-boat campaign, 1917-1918 , in Chickering and Forster (eds.). Great War, Total War, pp. 189-206. 

Clausius-Clapeyron equation, and to obtain a theoretical expression for a vapor bubble growing in a superheated liquid. The equation (F5, F6) is a second-order differential equation which is so complex as to be of limited usefulness without serious modification. Fortunately, the equation becomes enormously simpler if the inertia of the liquid can be ignored during bubble growth. Forster and Zuber give a careful discussion of the physical requirements for neglecting inertia of the liquid. These are that either the bubble must be very small or the temperature of the bubble... 

If the donor and acceptor molecules are unable to rotate in the solvent during the donor fluorescence time, the value of R0 considered above is too large. Steinberg [139] has analysed Forster kinetics in this limit. Allinger and Blumen [153] have developed a more detailed analysis of dipole—dipole energy transfer from excited donors to acceptors in liquids and obtained essentially similar results to those of Yokota and Tanimoto. 

Given the density of Chi in PSI, it is immediately obvious that any detailed description of energy transfer in this system will need to handle both weakly coupled (Forster-type) and strongly coupled (excitonic) systems self consistently. It is also evident that discerning rate limiting steps and optimizing principles may not be straightforward. 

The asymptotic value of s, so = 0.54, falls in between the predictions of Forster model, sa = 1/n2 = 0.5, which assumes infinitely thin point dipoles, and the Onsager value, sa = 3/( hr1 + 1) = 0.6, which considers point dipoles contained in spherical cavities. It is reasonable to think that real molecules fall in between these two limits. The solvent screening factors obtained for the data set, along with the fitted screening function, Eq. 14, and the Forster and Onsager values are plotted in Fig. 8. 

In contrast, studies aiming at determining the exact nature of the non-radiative deactivation mechanism and the corresponding mean distance of interaction appear to be more in line with the Forster theory spirit and may be regarded as a fascinating attempt in this field. However, applications appear rather limited as far as the question of the hydration sphere determination is concerned. 

The spectroscopic characteristics of actinide and lanthanide luminescent probes are sensitive to numerous parameters, such as modifications of solvent composition, addition of supporting electrolytes, temperature changes etc. Therefore, TRES appears as an interesting tool for the chemist, because it provides sensitive experimental data. However, the interactions between the probe and the surrounding medium (in a wide sense) appear to be intricate and difficult to handle. In this sense, attempts to describe lifetime variations as a function of a unique parameter, the hydration sphere number, have shown their limitations. On the other hand, the open questions related to Forster s mechanism are a vivid and still not fully explored field. 

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