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Diphenyl resonance energy

For symmetrical and unsymmetrical diphenyl-urea we expect some extra resonance energy in addition to that for two benzene rings and urea because of conjugation of these groups the values found are 0.55 v.e. and 0.50 v.e., respectively. [Pg.137]

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. [Pg.86]

Even having derived these resonance energies, it must be remembered that they are gross figures, which may be complicated by effects of strain and hybridization differences. Strain caused by the interaction of non-bonded atoms in diphenyl and similar molecules are particular cases of this. [Pg.85]

L. Davenport, R. E. Dale, R. H. Bisby, and R. B. Cundall, Transverse location of the fluorescent probe l,6-diphenyl-l,3,5-hexatriene in model lipid bilayer membrane systems by resonance excitation energy transfer, Biochemistry 24, 4097-4108 (1985). [Pg.267]

A combination of N CPMAS NMR, N quadrupole double resonance, and x-ray studies of solid 3,5-dimethylpyrazole (19) between 270 K and 350 K has been necessary to discuss the intermolecular proton transfer in a structure like (55) <89JA7304> the experimental evidence (species HHH and DDD) is consistent with a correlated triple hydrogen jump with an activation energy of 11 kcal mol". The cases of 3,5-diphenyl-4-bromopyrazole (a dimer like (54)) and 3,5-diphenyl-pyrazole (a tetramer like (56)) were subsequently studied <92JA9657> here also proton jumps were found with activation energies similar to those found for (19). The dynamic behavior of pyrazole... [Pg.15]


See other pages where Diphenyl resonance energy is mentioned: [Pg.126]    [Pg.644]    [Pg.540]    [Pg.636]    [Pg.960]    [Pg.960]    [Pg.540]    [Pg.636]    [Pg.960]    [Pg.960]    [Pg.644]    [Pg.345]    [Pg.324]    [Pg.75]    [Pg.1692]    [Pg.327]    [Pg.185]    [Pg.121]    [Pg.132]    [Pg.310]    [Pg.174]    [Pg.200]    [Pg.126]    [Pg.121]    [Pg.256]    [Pg.383]    [Pg.891]    [Pg.563]    [Pg.52]    [Pg.434]   
See also in sourсe #XX -- [ Pg.246 ]

See also in sourсe #XX -- [ Pg.246 ]




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