Xenon fluorescence quenching

The Dp and Dq are the diffusion coefficients of probe and quencher, respectively, N is the number molecules per millimole, andp is a factor that is related to the probability of each collision causing quenching and to the radius of interaction of probe and quencher. A more detailed treatment of fluorescence quenching including multiexponential intensity decays and static quenching is given elsewhere/635 There are many known collisional quenchers (analytes) which alter the fluorescence intensity and decay time. These include O2/19 2( 29 64 66) halides,(67 69) chlorinated hydrocarbons/705 iodide/715 bromate/725 xenon/735 acrylamide/745 succinimide/755 sulfur dioxide/765 and halothane/775 to name a few. 

A. R. Harrochs, A. Kearvell, K. Tickle, and F. Wilkinson, Mechanism of fluorescence quenching in solution II. Quenching by xenon and intersystem crossing efficiencies, Trans. Faraday Soc. 62, 3393-3399 (1966). 

Wilkinson has recently described a novel approach.113 It has long been known that solvents containing heavy atoms markedly quench the fluorescence of aromatic hydrocarbons, and it has been shown that this effect arises from an enhancement of the rate of intersystem crossing. Thus the ratio of phosphorescence to fluorescence for naphthalene irradiated at 77°K can be increased more than a hundredfold upon addition of some isopropyl iodide to the solvent.114 The same effect has been noted upon changing from hydrocarbon glasses to frozen krypton and xenon matrices.115 Wilkinson found that the decrease in fluorescence intensity from irradiated solutions of anthracene and some of its derivatives upon addition of bromobenzene is attended by an increase in T-T absorption intensity.116 The fluorescence quenching follows the Stern-Volmer law ... 

One common approach to fluorescence sensing is to rely on fluorophores which are collisionally quenched by the analyte. There are many known collisional quenchers (andytes) which alter the fluorescence intensity and decay time. These include O2 (27-31), chloride (32-33), chlorinated hydrocarbons (34), iodide (35), bromate (36), xenon (37), acrylamide (38), succinimide (39), sulfur dioxide (40), and halothane (41), to name a few. The quenching process obeys the Stem-Volmer equation ... 

With excitation at 280 nm the fluorescence of the indole ring in tryptophan is emitted with a maximum near 350 nm, and we followed the quenching of this fluorescence on reaction with NBS. The kinetic measurements were carried out using a Durrum stopped-flow instrument equipped with a 75 W Xenon-mercury lamp, and measurements were made of absorbance and of fluorescence. 

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