Red-edge effect

Demchenko AP (2008) Site-selective red-edge effects. Methods Enzymol 450 59-78... 

Demchenko AP, Sytnik AI (1991) Solvent reorganizational red-edge effect in intramolecular electron transfer. Proc Natl Acad Sci USA 88 9311-9314... 

Tomin VI, Brozis M, Heldt J (2003) The red edge effects in laurdan solutions. Z Naturforsch 58a 109-117... 

Keywords Excimers Intermolecular interactions Light-harvesting Red-edge effects Resonance energy transfer Superquenching Wavelength-shifting... 

Finally, it should be noted that homo-FRET, which is just the exchange of energies between the same dyes, is undetected by common spectroscopic or lifetime measurements and needs the hetero-FRET probing for its detection. The Red-Edge effect allows the easy distinguishing of the decrease of anisotropy due to FRET (static effect) from that occurring due to rotational freedom of fluorophores (dynamic effect), which does not depend on excitation wavelength. 

Engineering the rigidity of the dye environment and switching off the homo-FRET by variation of the excitation wavelength due to Red-Edge effect. 

Demchenko AP (2002) The red-edge effects 30 years of exploration. Luminescence 17 19-42... 

Homogeneous and inhomogeneous band broadening. Red-edge effects... 

Finally, there is a specific red-edge effect related to non-radiative energy transfer between a donor fluorophore whose emission spectrum overlaps the absorption spectrum of an acceptor fluorophore in rigid polar solutions, there is a lack of energy transfer upon excitation at the red-edge. This effect, called Weber s effect, will be described in Section 9.4.3. 

It should be recalled that, in polar rigid media, excitation on the red-edge of the absorption spectrum causes a red-shift of the fluorescence spectrum with respect to that observed on excitation in the bulk of the absorption spectrum (see the explanation of the red-edge effect in Section 3.5.1). Such a red-shift is still observable if the solvent relaxation competes with the fluorescence decay, but it disappears in fluid solutions because of dynamic equilibrium among the various solvation sites. 

Lack of energy transfer upon excitation at the red-edge of the absorption spectrum (Weber s red-edge effect)... 

K. A. Al-Hassan and T. Azumi, The red edge effect as a tool for investigating the origin of the anomalous fluorescence band of 9,9 -bianthryl in rigid polar polymer matrices, Chem. Phys. Lett, 150, 344 (1988). 

Here vmMn and vedge are the frequencies of the fluorescence spectra excited at fixed excitation frequencies at the maximum and at the red edge, respectively, and v a" — v dge is the limiting value of the red-edge effect, given by the... 

A comparison with the results of model studies indicates that the behavior of these probes bound to proteins differs fundamentally from their behavior in liquid media in which the position of their fluorescence spectra with ordinary excitation is similar to that for the protein complexes. In the latter case, the red-edge effect is always absent. 

Considerable red-edge effects exhibiting a dependence on the viscosity of the medium are observed for model solutions of indole and tryptophan(33) (Figure 2.11a), which permits this approach to be applied to studies of the dynamics of the environment of tryptophan residues in proteins. In discussion... 

---