摘要:

The scintillation efficiency of a benzene + p-terphenyl solution, extrapolated to unit energy transfer efficiency, has been determined to be 0.042 (or equivalently 0.0116 ± .004 photon/ev). This corresponds to a G value for production of1B2ubenzene of 1.55 ± .05. It is suggested that the difference between this value and that for other alkyl benzene liquids (1.9–2.5) and for anthracene crystal (2.20) is related to the efficiency with which upper states of these substances make internal conversion to the emitting or transferring state.

ISSN:0369-1152    

DOI:10.1080/15421406808082897

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The overall fluorescence yield and fluorescence spectrum of polystyrene as well as the fluorescence yield of solid solutions of anthracene and of diphenyloxazole in polystyrene are studied as a function of excitation wavelength in the region 584–3000 Å. In all cases a strong dependence of the investigated properties on excitation wavelength is found.

ISSN:0369-1152    

DOI:10.1080/15421406808082898

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The quenching of benzene monomer fluorescence by biacetyl at 28°C is studied as a function of dilution with hexane and cyclohexane. The component of the overall transfer rate constant, attributable to solvent-solvent energy migration is shown to vary linearly with benzene concentration and is independent of the diluent. The results are discussed in the light of the work of other authors.

ISSN:0369-1152    

DOI:10.1080/15421406808082899

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Many studies have been carried out on the measurements of luminescence yields as a function of the solute concentrations in aromatic solvents. Most of these have been done at moderate solute concentrations, between 0.1 and 20 g/l. The scope of this work was a study of the luminescence yield at low solute concentrations, down to 0.005 g/l. Only at these low concentrations is it possible to get information on other processes which might occur in the liquid scintillator solution system. Of particular interest is the measurement of the contribution to the luminescence yield of a possible radiative transfer process at low solute concentrations.

ISSN:0369-1152    

DOI:10.1080/15421406808082900

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Data on the kinetics of processes involving radiation protection, luminescence and luminescence quenching in cyclohexane solutions as well as on absorption spectra and luminescence of aliphatic glasses are briefly reviewed. It is concluded that energy transfer in a cyclohexane system cannot involve excitation transfer from single excited cyclohexane molecules. The Laor-Weinreb results1are explicable on the basis of charge transfer.

ISSN:0369-1152    

DOI:10.1080/15421406808082901

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The quenching of the fluorescence of anthracene and some of its meso-derivatives by “heavy atom quenchers” in various solvents has been shown to be dependent on the solvent, the quencher, and especially on the nature of the substituent. Anthracene shows good agreement with the Stern-Volmer equation in all solvents even in the presence of very high concentrations of quencher. However, marked deviations from this equation are observed for certain anthracene derivatives and in some cases the heavy atom “quencher” leads to an increase rather than to a decrease in the fluorescence.

ISSN:0369-1152    

DOI:10.1080/15421406808082902

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Luminescence quenching in polystyrene + 9,10-diphenylanthracene + quencher and polystyrene + quencher systems has been investigated. In the latter system, the residual styrene monomer is regarded as a fluorescent solute. Result show that solvent quenching observed under uv excitation is due mainly to the competition between dipole-dipole energy transfer from polystyrene to the fluor and that from polystyrene to the quencher, and that such a transfer occurs directly from an excited polystyrene segment before it forms an excimer with an unexcited segment. Solvent quenching under beta-ray excitation was generally greater than that under uv excitation. It is suggested that this phenomenon may result from the occurrence of energy transfer at higher excited state of polystyrene. Solute quenching in some series of polystyrene + 9,10-diphenylanthracene + quencher is not accounted for by usual mechanisms of quenching. Such quenching can be explained by assuming energy transfer from the singlet excited state of 9,10-diphenylanthracene to the triplet state of the quencher.

ISSN:0369-1152    

DOI:10.1080/15421406808082903

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Perrin's equation for solute quenching is redefined. Multicomponent concentration quenching curves are obtained by plotting log (I/c) vs. c. Addition of quencher to the solvent-solute system and use of inefficient solvent cause the quenching curves to become linear. Based on the shift of maximum activating wavelength during photo-activation, formation of excimers or molecular aggregates of similar nature is postulated to explain the observed phenomenon.

ISSN:0369-1152    

DOI:10.1080/15421406808082904

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Results obtained in the laboratory on the luminescence decay of organic scintillators are reviewed. Theoretical equations, resulting from an analysis of the scintillation process, are shown to be in good agreement with experimental decay curves obtained with crystals and liquid scintillators. The pulse shape discrimination of particles is discussed, and a technique allowing to separate α-particles, protons and β-rays if presented.

ISSN:0369-1152    

DOI:10.1080/15421406808082905

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The development of fast electro-optical instrumentation over the last ten years1–9has not only extended dynamic luminescence studies into the range of a few nanoseconds but also made such studies possible with low light intensities. Measurement of luminescence-decay curves over several decades of intensity variation are now feasible.

ISSN:0369-1152    

DOI:10.1080/15421406808082906

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor