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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
Thermally activated delayed fluorescence (TADF) is a process through which surrounding thermal energy changes population of excited states of molecular compounds and thus, alters light emission. The TADF process usually involves an excited molecular species in a triplet state , which commonly has a forbidden transition to the singlet ground ...
Fluorescence spectroscopy (also known as fluorimetry or spectrofluorometry) is a type of electromagnetic spectroscopy that analyzes fluorescence from a sample. It involves using a beam of light, usually ultraviolet light , that excites the electrons in molecules of certain compounds and causes them to emit light; typically, but not necessarily ...
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 ...
YFP fluorescence is sensitive to various small anions with relative potencies iodine > nitrate > chloride > bromide > formate > acetate. [2] YFP sensitivity to these small anions results from ground-state binding near the chromophore , [ 3 ] which apparently alters the chromophore ionization constant and hence the fluorescence emission.
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.
This fluorescence quenching response can be exploited for detecting the opening of the mitochondrial permeability transition pore (mPTP) and for measuring cell volume changes. [5] Calcein is commonly used for cell tracing and in studies of endocytosis, cell migration, and gap junctions.
If the topology of a cell membrane is undetermined, epitope insertion into proteins can be used in conjunction with immunofluorescence to determine structures within the cell membrane. [9] Immunofluorescence (IF) can also be used as a “semi-quantitative” method to gain insight into the levels and localization patterns of DNA methylation.