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The chloride ion is a well known quencher for quinine fluorescence. [2] [3] [4] Quenching poses a problem for non-instant spectroscopic methods, such as laser-induced fluorescence. Quenching is made use of in optode sensors; for instance the quenching effect of oxygen on certain ruthenium complexes allows the measurement of oxygen saturation in
The quencher then returns to the ground state through emissive decay (fluorescence) or nonradiatively (dark quenching). In nonradiative or dark decay, energy is given off via molecular vibrations (heat). With the typical μM or less concentration of sample, the heat from radiationless decay is too small to affect the temperature of the solution.
For diffusion-limited quenching (i.e., quenching in which the time for quencher particles to diffuse toward and collide with excited particles is the limiting factor, and almost all such collisions are effective), the quenching rate coefficient is given by = /, where is the ideal gas constant, is temperature in kelvins and is the viscosity of ...
Therefore, photochemical quenching increases with the time of illumination, with a corresponding increase of the fluorescence intensity. The slow decrease of the fluorescence intensity at later times is caused, in addition to other processes, by non-photochemical quenching. Non-photochemical quenching is a protection mechanism in photosynthetic ...
A simplified Jablonski diagram illustrating the change of energy levels.. The principle behind fluorescence is that the fluorescent moiety contains electrons which can absorb a photon and briefly enter an excited state before either dispersing the energy non-radiatively or emitting it as a photon, but with a lower energy, i.e., at a longer wavelength (wavelength and energy are inversely ...
The efficiency of photochemical quenching (which is a proxy of the efficiency of PSII) can be estimated by comparing to the steady yield of fluorescence in the light and the yield of fluorescence in the absence of photosynthetic light . The efficiency of non-photochemical quenching is altered by various internal and external factors.
The relation is: = +. where L is the light yield, S is the scintillation efficiency, dE/dx is the specific energy loss of the particle per path length, k is the probability of quenching, [1] and B is a constant of proportionality linking the local density of ionized molecules at a point along the particle's path to the specific energy loss; [1] "Since k and B appear only as a product, they act ...
Biofluorescence is frequent in plants, and can occur in many of their parts. [4] The biofluorescence in chlorophyll but has been studied since the 1800s. [5] Generally, chlorophyll fluoresces red, [6] and can be used as a measure of photosynthetic capabilities, [7] [6] or general health. [5]