The quenching of System Ii fluorescence bv System I light was discovered in 196o (ref. I) and was later investigated in detail 2-~. DUYSENS AND SWEEI~S a suggested that System II reduces a compound "Q" , and System I oxidizes this reduced Q back to its oxidized form. The Q in the oxidized, but not in the reduced, form is a quencher of fluorescence. We have measured the time dependence of this q...

We have examined the quenching of pyrochlorophyll fluorescence by a series of substituted nitrobenzenes in ethanol-pyridine solution and the effect of fluorescence quenching on the quantum yield of sensitized photoreduction of three of the nitro compounds by hydrazobenzene. All nitro compounds examined are at least moderately good quenchers of fluorescence. There is a good correlation between t...

Perylene bisimide and triphenyl diamine are prototypical organic dyes frequently used in organic solar cells and light emitting devices. Recent Forster-resonant-energy-transfer experiments on a bridged organic dyad consisting of triphenyl diamine as an energy-donor and perylene bisimide as an energy-acceptor revealed a strong fluorescence quenching on the perylene bisimide. This quenching is ab...

Fluorescence quenching of pyranine by tryptophan, phenylalanine, and nicotinic acid was investigated by using steady state and time resolved fluorescence spectroscopy. On a comparative basis, nicotinic acid is a very strong quencher of pyranine fluorescence, tryptophan is a moderate quencher and phenylalanine is a weak quencher. The strong quenching is the result of the hydrogen bonding complex...

The two pulse fluorescence bleaching experiments reported in an earlier paper @J. Chem. Phys. 117, 454 ~2002!# are reanalyzed in the context of additional experiments. The fluorescence bleaching observed in that paper was originally ascribed to ground-state depletion. By analyzing the absorption saturation behavior and the magnitude of the pump–probe signal, we find that the absorption cross se...

The azaoxa-triangulenium dyes are characterised by emission in the red and a long fluorescence lifetime (up to 25 ns). These properties have been widely explored for the azadioxatrianguelnium (ADOTA) dye. Here, the syntheses of reactive maleimide and NHS-ester forms of the diazaoxatriangulenium (DAOTA) system are reported. The DAOTA fluorophore was conjugated to bovine serum albumin (BSA) and i...

Two current technologies used in biosensor development are very promising: 1. The sol-gel process of making microporous glass at room temperature, and 2. Using a fluorescent compound that undergoes fluorescence quenching in response to a specific analyte. These technologies have been combined to produce an iron biosensor. To optimize the iron (II or III) specificity of an iron biosensor, pyover...

In 2005, it was found that the fluorescence of crystals of the major light-harvesting complex LHCII of green plants is significantly quenched when compared to the fluorescence of isolated LHCII (A. A. Pascal et al., Nature, 2005, 436, 134–137). The Raman spectrum of crystallized LHCII was also found to be different from that of isolated LHCII but very similar to that of aggregated LHCII, which ...

The excited state isomerization of thioflavin T (ThT) is responsible for the quenching of its fluorescence in a nonrestricted environment. The fluorescence quantum yield increases substantially upon binding to amyloid fibers. Simulations reveal that the variation of the twisting angle between benzothiazole and benzene groups (φ1) is responsible for the subpicosecond fluorescence quenching. The ...

In this report, we systematically studied the effects of different metal ions on the fluorescence of common thiolate ligand capped quantum dots. Generally, heavy metal ions exhibited much more significant fluorescence quenching. Also, the coordination capability and steric hindrance of the ligand jointly affect the quenching efficiency.