Quenching efficiencies

Heat recovery tor steam generation, pre-heating combustion air, and high efficiency burners Adjustable speed drives, heat recovery coke oven gases, and dry coke quenching Efficient hot blast stove operation, waste heat recovery for hot blast stove, top gas power recovery turbines, direct coal injection... 

Kaneko et al. [80, 81] prepared copolymers of AA (93.9-95.9 mol%) and vinylbipyridine (1.6-3.7 mol%) with pendant Ru(bpy)2+ (2.4-2.5 mol%) (25). The quenching of the excited state of the pendant Ru(II) complex by MV2+ was accelerated in alkaline aqueous solution owing to the electrostatic attraction of the cationic quencher. Interestingly, the quenching efficiency was dependent on the molecular weight of 25. The quenching of the polymer with MW 2100 occurred... 

Despite the fact that the Phen moieties are tightly incorporated in the compartment of the hydrophobic microdomain, the fluorescence from the Phen residues in poly(A/St/Phen) is very efficiently quenched by MV2+ in aqueous solution. The quenching efficiency is much higher than the APh-2 (8 with x = 2)... 

From the relation between the quenching efficiency and the charge separation efficiency Webber et al. [77] and Morishima et al. [76, 119, 120] have reached the same conclusion that efficient fluorescence quenching static in nature does not lead to efficient charge separation. This conclusion seems to apply generally to... 

There is a small correction factor which takes into account the quenching efficiency of the antibody and the r value for FLPEP on the antibody.)... 

A further interesting application of CLM involves the fluorescence quenching reaction between (5,10,15,20-tetraphenylporphyrinato) zinc (II) and methylviologen at a dode-cane-water interface. [62] This study demonstrated that the quenching reaction could occur only in the presence of an anionic surfactant, sodium dodecyl sulfate (SDS). The quenching efficiency depended on the concentration of SDS in the aqueous phase with a maximum value of 13.5%... 

Depending on the relief stream components (with or without noncondensable gases) and quenching efficiency, this arrangement often obviates the need for a subsequent scrubber and/or flare stack. The design of the quencher arm is critical to efficient condensation and avoidance of water hammer. Figure 23-55 is the more conventional passive type quench pool used in the chemical and nuclear industry. 

It should also be noted that comparison of quenching efficiency of conjugated polymers with small-molecule fluorophores is complicated and oversimplification can lead to misleading claims of exceptional sensitivity enhancements. In their 2007 review, Swager and co-workers discuss cases where the charge state of the small molecule used for comparison differed fundamentally from the polymer and exceptional quenching efficiencies were inappropriately attributed to super-quenching alone [3], In addition, a polymer will create a different local... 

Emission quenching is also observed with mononucleotides. In that case the quenching efficiency decreases from GMP (guanosine 5 monophosphate) to AMP (adenosine 5 monophosphate) i.e. it also follows the redox potentials of the bases, as G is more easily oxidisable than A, although the oxidation potential valura reported in the literature are rather different from one author to the other [101-104], Moreover the quenching rate constant by GMP in a Kries of different TAP and HAT complexes plotted versus the reduction potential of the excited state (Fig. 12) [95] is consistent with an electron transfer process. Indeed, as will be demonstrated in Sect. 4.3.1, these quenchings (by the mono-and polynucleotides) originate from such processes. 

Semiconductor nanoclusters trapped in AOT w/o microemulsions are reported to exhibit longer excited state lifetimes (about 10-100 ns) than those in aqueous solution or in monophasic organic solvents [213]. Clearly the surfactant-nanoparticle interaction is very important not only in restricting growth but also in extending the hfetimes of the excited states. Tata et al. [214] have shown that the removal of water from the micelles leads to a strong increase in fluorescence intensity, and the addition of specific quencher, 4-hydroxythiophenol, leads to variations in quenching efficiencies. 

Direct evidence for triplet-triplet transfer has been provided by sensitizing both the isomerization of cis- or ira/w-olefins,28 38 79,80 and the dimerization of some cyclic olefins81-83 with carbonyl compounds. Furthermore, the phosphorescence of some carbonyl compounds can be quenched by olefins (for example, acetone with 2-pentene30 and phenyl-cyclopropyl ketone with 2-methyl-2-butene37). On the other hand, the phosphorescence of benzophenone is not quenched by 2-methyl-2-butene37 nor is the photoreduction of benzophenone quenched efficiently by cyclohexene (Table II). 

Since the quenching efficiency depends, in part, upon the difference in energy of the excited states (being very efficient when the transfer is exothermic, but perhaps possible with diminishing efficiency when the process is endothermic84) the importance of knowing the carbonyl n,n triplet energy is obvious. 

The very wide range of quenching efficiencies exhibited by different quenchers under the same conditions (cf. Table I) can be rationalized in terms of reversible photoassociation and provides indirect evidence for this phenomenon. Thus if KQ is significantly less than kdrf it may be assumed that kitcTF 1 and Eq. (32) reduces to... 

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