Ultratrace analysis of transuranic actinides by laser-induced fluorescence
First Claim
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1. A method for detecting ultratrace quantities of weakly or non-fluorescing transuranic actinides in water, the method comprising the steps of:
- (a) copreciptating an actinide in a water sample with host precursor materials to form a precipitate, the precipitate comprising a preselected host material which includes at least one fluorescent component species having a near resonant energy level with the actinide and whose fluorescence is quenched or sensitized by the actinide;
(b) illuminating the precipitate with laser light of a preselected wavelength, said wavelength being selected in the case of sensitizing by the actinide to excite the actinide to a level above and sufficiently close to the near resonant energy level of the at least one fluorescent component species to cause substantial nonradiative decay from the actinide to the near resonant energy level, said wavelength being selected in the case of quenching by the actinide to excite the at least one fluorescent component species to the near resonant energy level, so that the at least one fluoroescent component species is caused to fluoresce and energy is transferred between the near resonant energy level of the at least one fluorescent component species and the actinide;
(c) measuring a difference in intensity between the fluorescence of the at least one fluorescent component species which has been quenched or sensitized by the actinide from the sample and the fluorescence of the at least one fluorescent component species in at least one standard, said at least one standard having been prepared with a known concentration of the actinide; and
(d) determining the concentration of the actinide in the sample by relating the difference in the fluorescence intensity to quantitative differences between the concentration of the actinide in the sample and the concentrations of the actinide in said at least one standard.
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Abstract
Ultratrace quantities of transuranic actinides are detected indirectly by their effect on the fluorescent emissions of a preselected fluorescent species. Transuranic actinides in a sample are coprecipitated with a host lattice material containing at least one preselected fluorescent species. The actinide either quenches or enhances the laser-induced fluorescence of the preselected fluorescent species. The degree of enhancement or quenching is quantitatively related to the concentration of actinide in the sample.
33 Citations
20 Claims
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1. A method for detecting ultratrace quantities of weakly or non-fluorescing transuranic actinides in water, the method comprising the steps of:
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(a) copreciptating an actinide in a water sample with host precursor materials to form a precipitate, the precipitate comprising a preselected host material which includes at least one fluorescent component species having a near resonant energy level with the actinide and whose fluorescence is quenched or sensitized by the actinide; (b) illuminating the precipitate with laser light of a preselected wavelength, said wavelength being selected in the case of sensitizing by the actinide to excite the actinide to a level above and sufficiently close to the near resonant energy level of the at least one fluorescent component species to cause substantial nonradiative decay from the actinide to the near resonant energy level, said wavelength being selected in the case of quenching by the actinide to excite the at least one fluorescent component species to the near resonant energy level, so that the at least one fluoroescent component species is caused to fluoresce and energy is transferred between the near resonant energy level of the at least one fluorescent component species and the actinide; (c) measuring a difference in intensity between the fluorescence of the at least one fluorescent component species which has been quenched or sensitized by the actinide from the sample and the fluorescence of the at least one fluorescent component species in at least one standard, said at least one standard having been prepared with a known concentration of the actinide; and (d) determining the concentration of the actinide in the sample by relating the difference in the fluorescence intensity to quantitative differences between the concentration of the actinide in the sample and the concentrations of the actinide in said at least one standard. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 20)
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18. (d) said step of measuring includes measuring the difference between the intensity of terbium fluorescence in the calcined precipitate containing americium from the sample and the intensity of terbium fluorescence in said at least one standard, said at least one standard having been prepared with a known concentration of americium;
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19. (e) said step of determining includes determining the concentration of americium in said sample by relating the difference in terbium fluorescence intensity to quantitative differences between the concentration of americium in said sample and the concentrations of americium in said at least one standard.
Specification