Donor transfer

Values of CP measured in the presence of added PMMA (for example) will depend on how the PMMA was prepared and its molecular weight (i.e. on the concentration of unsaturated ends). PMMA formed by radical polymerization in the presence of a good H-donor transfer agent (or by anionic polymerization) would have only saturated chain ends. These PMMA chains should have a different transfer constant to those formed by normal radical polymerization where termination occurs by a mixture of combination and disproportionation. This could account for some of the variation in the values of CP for this polymer... 

First entry on each line is the tag. Square brackets enclose the probe donor + transfer enzyme (where applicable) or reaction. Probe organic fluorophores, nanoparticles (can be QDs as in methods 2, 3, 8, 9) or a bridging/recognition moiety. If desired, the latter can serve in a second orthogonal reaction ( piggyback strategy). See text. Biotin readout probes linked to avidin, streptavidin, anti-biotin 7[101] ... 

The authors suggest that the photoexdted electron donor transfers an electron to the sulfonyl group of the tosylamine to provide an anion-radical that undergoes a heterolytic S — N bond cleavage to produce the deblocked amine after protonation as well as tosylsulfonic and sulfuric add. The function of the reducing agent is to reduce spedes such as the dimethoxybenzene cation-radical and the sulfonyl radical. 

The compression towards the active site revealed in Fig. 24 is what causes the donor-acceptor distances for the hydride and proton transfers to reach their minimum. When they reach their minimum, interactions across the donor, transferring atom, and acceptor are initiated. The events that occur next are critical for... 

As expected, the inferred value for rF turned out to be larger than the value based upon the spectral overlap integral because that analysis ignores donor-donor transfer prior to donor-acceptor transfer. The current theory takes proper account of this fact. 

FRET is the process by which one fluorophore, "the donor," transfers energy to a second fluorophore, "the acceptor." When both chromophores are fluorescent, FRET occurs. In the case of FRET between fluorophores, the emission spectrum of the donor fluorophore must overlap with the absorption spectrum of the acceptor. In this case, the emission from the donor excites the acceptor causing it to emit light (fluoresce). The efficiency of FRET depends on the distance between the two fluorophores, the spectral overlap, and the relative orientations between the donor emission dipole and the acceptor absorption dipole. 

Fig. 11. Schematic representation of transfer processes observed within an inhomogeneously broadened line using pulsed TRFLN. Experimental traces illustrate the dynamics observed within the P state of Pr iLaF, as a function of time. Information on the microscopic interactions producing the transfer are carried in the manner in which the background develops. TRFLN has proven very useful in the study of like-ion or donor-donor transfer. Data from Huber et al. (1977).

Conventional spectroscopic methods have been more than adequate to demonstrate the existence of donor to acceptor transfer and have allowed the extraction of the donor to acceptor transfer rates in a variety of lanthanide doped solids. In order to accomplish this extraction, a model is assumed to fit an observed decay. Implicit in this assumption is an estimate of the relative magnitude of the donor to donor transfer rate relative to the donor to acceptor rate. The former cannot be easily measured directly using broad band sources. 

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