Phosphorescence quenching, correlation

In the frame of CSTPM, the following dynamics parameters of the cascade system components can be experimentally measured the spin label rotation correlation time and spin relaxation parameters, the fluorescence and phosphorescence polarization correlation times, the singlet and triplet state quenching rate constants, the rate constant of photoisomerization, and the rate constant of the triplet-triplet energy transfer. This set of parameters is a cumulative characteristic of the dynamic state of biomembranes in the wide range of the probes amplitude and characteristic time. 

A survey of the quenching constants for a series of proteins was made using one quencher, nitrite (Table 3.4).(58) It is noted that the phosphorescence lifetime t0 is not correlated with the quenching constant. For example, the... 

A third method of looking for triplet-state intermediates in a reaction is to correlate the extent of quenching of phosphorescence of an excited species with the amount of chemical reaction under the specific reaction conditions. The possibility of this has led to numerous measurements of the fluorescence and phosphorescence of the pyrimidines and purines. 

Several years ago it was found that many aromatic carbonyl compounds are photoreduced by aliphatic and aromatic amines (Cohen et al., 1973 Davidson, 1975). It was suggested that these reactions proceed by electron transfer from the amine to the triplet carbonyl compound. Evidence in support of this mechanism was that the ability of amines to quench the phosphorescence of carbonyl compounds, and to react with them, correlated with the ionisation potential of the amines. On the basis of this evidence the reaction scheme in... 

Since the determination of inhibitors in polymers by Drushel et al. [13] little information has been added to the literature on the quantitative aspects of the direct examination of polymer films by phosphorescence spectroscopy. These authors examined phosphorescence (at liquid-nitrogen temperature) of thin EPR films containing Santonox R (2,2 -di-methyl-5,5 -di-r -butyl-4,4 -dihydroxydiphenyl sulfide) and V-phenyl-2-naphthyl-amine (PBN). The rather intense phosphorescence of PBN may be used to advantage when other additives interfere in the UV absorption method. As to quantitative phosphorescence analysis, several factors, e.g. film thickness, concentration quenching, and background absorption, etc., affect the linearity of the analytical working curves and precision of the measurements [13]. The reliability of a correlation between stabiliser concentration in the film and phosphorescence intensity at 77 K is also influenced by the degree of crystallinity [544]. 

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