Bimolecular quenching processes in solution

Bowen, E. J.; Barnes, A. W.; Holliday, P.

doi:10.1039/tf9474300027

Cited by 11 publications

(5 citation statements)

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“…This corresponds to a quenching radius of about 30 A. Transfer of electronic energy is believed to take place over distances as large as this where there are conditions of resonance (Bowen, Mikiewicz & Smith 1949;Forster 1948Forster , 1949, but intermolecular resonance does not seem to occur in the above molecules. If it is assumed th a t in the absence of energy resonance, quenching should not occur at distances greater than one molecular diameter (about 6 A), and that all the molecules are randomly arranged, K would not be expected to exceed 0*5.…”

Section: Theoretical Considerationsmentioning

confidence: 96%

“…The distribution of collisions which is diffusion and viscosity controlled is no longer of importance, and the fact th a t the effectiveness of such weak quenchers as carbon tetrachloride and bromobenzene ( k« 1) is independent of the viscosity in paraffin sol the view th a t the average collision frequency is not related to diffusion rates or solvent viscosity. The intermediate case of quenchers of moderate efficiency such as bromoform (Bowen, Barnes & Holliday 1947), where the number of collisions in encounters is of the same order as the number of collisions required for quenching to occur is one whose ^quantitative treatm ent is more difficult.…”

Section: Theoretical Considerationsmentioning

confidence: 99%

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The quenching of anthracene fluorescence

Bowen

Metcalf

1951

Proc. R. Soc. Lond. A

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The quenching of the fluorescence of anthracene excited by light of wave-length 3650 Å by oxygen, sulphur dioxide, and by carbon tetrabromide, has been investigated both in the gaseous state and in paraffin solutions of viscosities from 0·003 to 1·9 poises. In the gaseous state quenching occurs on nearly every collision. The quenching in dilute solution is shown to be controlled ( a ) by static quenching whereby light is absorbed by anthracene molecules contiguous to quencher molecules, and ( b ) by the diffusion together of excited molecules and quencher molecules. The former process is of greater importance in solutions of high viscosity. The latter predominates at more usual viscosities, and is found to be more nearly proportional to the diffusion coefficient of anthracene than to the fluidity of the solvent. Measured diffusional quenching constants are in good agreement with calculated values. The magnitudes of static constants indicate that in solutions containing anthracene and a quenching substance the two solutes are not randomly distributed but tend to associate with one another.

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Section: Theoretical Considerationsmentioning

confidence: 96%

Section: Theoretical Considerationsmentioning

confidence: 99%

The quenching of anthracene fluorescence

Bowen

Metcalf

1951

Proc. R. Soc. Lond. A

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“…At this concentration the quenching is probably non-collisional and may be envisaged as the transport of H+ ion by the CO2 group from the solution to the neighbourhood of the excited molecule. For collisional quenching one or more collisions must occur during the lifetime of the excited state (Bowen, Barnes & Holliday, 1947;Umberger & la Mer, 1945). From diffusion theory, Z = 1010. cr, where Z = number of collisions/sec., c = molar concentration of quencher, =lifetime of the excited state, with =10-8 sec.…”

Section: Tyro8ine and Derivativesmentioning

confidence: 99%

Effect of pH on fluorescence of tyrosine, tryptophan and related compounds

White

1959

Biochemical Journal

200

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Unlike the absorption spectrum, the fluorescence spectrum of proteins is not the simple sum of the contributions of the aromatic amino acids in neutral water solutions (Teale & Weber, 1956). A study of the behaviour of substituted aromatic amino acids and simple peptides was undertaken in an attempt to elucidate phenomena contributing to the fluorescence of proteins. Ultraviolet excitation was used to reach the lowest excited singlet state of the compounds and interest was concentrated in energy loss by processes competing with fluorescence, i.e. a reduction in the quantum yield of fluorescence. The changes in fluorescence yield with hydrogen-ion concentration were studied. EXPERIMENTAL Methods The fluorescence-excitation spectra were determined by means of the apparatus described by Teale & Weber (1956). Briefly, the principle was to irradiate a cell containing the test solution with monochromatic light and to view the light emitted at right-angles to the incident light by means of a photomultiplier. A filter to block any scattered exciting light was interposed between the cell and the photomultiplier. The photomultiplier was an EMI 6255 or 27M3 Mazda. A Perspex filter absorbing light of wavelengths less than 300 m,u was used to separate exciting light and fluorescence.

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“…I n contrast to the above "inner-filter" type of quenching is the " collisional " type showing a positive temperature coefficient.11, 27, 28,29,30 Collisions in liquids differ from those in gases in being "repeated," and a distinction must be drawn between '( encounter frequency " and " collisional frequency." As in many cases of quenching the actual molecular process is very efficient, occurring after one or a very few collisions, rates of quenching must be related to (' encounter " and not t o " collisional" frequencies, and the former vary as the temperature and inversely as the viscosity.…”

Section: Fiqmentioning

confidence: 99%