Anion coordination to uranyl ion and the luminescence lifetime of the uranyl complex

Moriyasu, Masataka; Yokoyama, Yû; Ikeda, Shigerô

doi:10.1016/0022-1902(77)80395-3

Cited by 56 publications

(56 citation statements)

References 9 publications

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“…The much longer luminescence lifetimes observed in the present work and also reported by Moulin and coworkers in 0.67 M HF [7], in comparison with those reported by Moriyasu and coworkers [5] and Billing and coworkers [6], can be understood in terms of uranyl fluoride equilibria that are influenced by whether or not such complexes are electronically excited. If we assume that equilibrium occurs, on the time scale of the observed luminescence, among U02F', U02F2, U02F3-, and U02F42-and F-, for electronicallv excited uranvl species (denoted by an asterisk in equilibrium reactions), we can model the observed data shown in Fig.…”

Section: Resultssupporting

confidence: 85%

“…2) [5]. They reported that the luminescence decay rate of U02F+ is 13333 s-' and the decay rates of U02F2, U02F3-, and U02F42-are the same (6667 s") to within an unstated error limit.…”

Section: Resultsmentioning

confidence: 96%

“…However, several luminescence studies, including work on uranyl sulfate [18] and nitrate [19] complexes, have concluded that ligand exchange rates for complexes of electronically excited uranyl can be so rapid that equilibrium is achieved on the luminescence time scale. Fixing the luminescence decay rate of U02F' at 13333 s-' [5] and that of UOzF42-at 6250 s-' [6] and carrying out nonlinear least squares adjustment, gives the solid line shown in Fig. 3 for fit values of 8044 M-' for the equilibrium constant for formation of U02F2* via U02F+* + F-+ U02F2*, of 0.7868 M-' for formation of U02F3-* via U02F2* + F-+ U02F3-*, of 1.053~10-~ M-' for formation of U02F42-* via U02F3-* + F--+ U02F42-* and of 3799 s-l and 11850 s-' as the luminescence decay rates of U02F2 and UO2F3-, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…The study of Kaminski and coworkers [4] provides an example of such work and they cite earlier analytical studies. Moriyasu and coworkers [5] carried out a systematic study of the influence of fluoride on the luminescence lifetimes of 0.01 M uranyl solutions. They reported that the uranyl luminescence decay rate at 298 K decreased with increasing fluoride concentration to a value, 6667 s-', that remained constant from 0.06 M to 1 M fluoride and concluded that U02F2, U02F3', and U02F: ' have the same luminescence lifetimes.…”

Section: Introductionmentioning

confidence: 99%

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Uranyl fluoride luminescence in acidic aqueous solutions

Beitz¹,

Williams²

1997

Journal of Alloys and Compounds

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Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 f 0.006 ms, was observed from uranyl in 1 M HF + 1 M HC104 at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to U02F2. Studies on the effect of added LiN03 or Na2W04'2Hz0 showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the u F 6 content of w F 6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure w F 6 .

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Section: Resultssupporting

confidence: 85%

“…2) [5]. They reported that the luminescence decay rate of U02F+ is 13333 s-' and the decay rates of U02F2, U02F3-, and U02F42-are the same (6667 s") to within an unstated error limit.…”

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Uranyl fluoride luminescence in acidic aqueous solutions

Beitz¹,

Williams²

1997

Journal of Alloys and Compounds

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“…27 Finally, another publication states that the free UO 2 2+ aq and the two first successive fluoride complexes lead to multiexponential behavior of the decays. 28 All these experimental studies were performed for different ionic strengths and overall chemical compositions of the samples, that are also different from the chemical conditions prevailing in sample B.…”

Section: +mentioning

confidence: 99%

Aqueous Solutions of Uranium(VI) as Studied by Time-Resolved Emission Spectroscopy: A Round-Robin Test

et al. 2003

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Results are presented of an interlaboratory round-robin study of the application of timeResolved Emission Spectroscopy (TRES) to the speciation of uranium(VI) in aqueous media. This involved 13 independent laboratories, using various instrumental adevices and data 2 analysis methods. In some cases, experimental data from a laboratory were analysed using different softwares. Samples were prepared based on appropriate speciation diagrams and in general were found to be chemically stable for at least six months. Four different types of aqueous uranyl solutions were studied: (i) acidic medium where UO 2 2+ aq is the single emitting species, (ii) uranyl in the presence of fluoride ions, (iii) uranyl in the presence of sulfate ions, and (iv) uranyl in aqueous solutions under various pH conditions, promoting hydrolysed species. Results between the laboratories are compared in terms of number of decay components, luminescence lifetimes and spectral band positions. The potentials and limitations of TRES in uranyl analysis and speciation in aqueous solutions are discussed.

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