Differences of Eu(iii) and Cm(iii) chemistry in ionic liquids: investigations by TRLFS

Abstract

In this study the coordination structure and chemistry of Eu(III) and Cm(III) in the ionic liquid C(4)mimTf(2)N (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) was investigated by time-resolved laser fluorescence spectroscopy (TRLFS). The dissolution of 1 x 10(-2) M Eu(CF(3)SO(3))(3) and 1 x 10(-7) M Cm(ClO(4))(3) in C(4)mimTf(2)N leads to the formation of two species for each cation with fluorescence emission lifetimes of 2.5 +/- 0.2 ms and 1.0 +/- 0.3 ms for the Eu-species and 1.0 +/- 0.3 ms and 300.0 +/- 50 micros for the Cm-species. The interpretation of the TRLFS data indicates a comparable coordination for both the lanthanide and actinide cation in this ionic liquid. The quenching influence of Cu(II) on the fluorescence emission of Eu(III) and Cm(III) was also measured by TRLFS. While Cu(ii) does not quench the Cm(III) fluorescence emission in C(4)mimTf(2)N the Eu(III) fluorescence emission lifetime for both Eu-species in C(4)mimTf(2)N decreases with increasing Cu(II) concentration. Stern-Volmer constants were calculated (k(SV) = 1.54 x 10(6) M(-1) s(-1) and k(SV) = 2.70 x 10(6) M(-1)). By contrast, the interaction of Cu(II) with Eu(III) and Cm(III) in water leads to a quenching of both the lanthanide and actinide fluorescence. The calculated Stern-Volmer constants are 1.20 x 10(4) M(-1) s(-1) for Eu(III) and 1.27 x 10(4) M(-1) s(-1) for Cm(III). The investigations show, while the chemistry of trivalent lanthanides and actinides is similar in an aqueous system it is dramatically different in ionic liquids. This difference in chemical behavior may provide the opportunity for a separation of lanthanides and actinides with regard to the reprocessing of nuclear fuel.

Reactivity Towards Europium(III) of the Radiolysis Products of the Ionic Liquid 1‐Methyl‐3‐butyl‐1H‐imidazolium Bis[(trifluoromethyl)sulfonyl]amide (C4‐mimTf2N) and Effect of Water: A TRLFS (Time‐Resolved Laser‐Induced Fluorescence Spectroscopy) Preliminary Study

“…Second, the solutions have been dried after introduction of the europium salt so that both the latter and the solvent were dried together, leading to a total amount of remaining H 2 O (as measured by Karl -Fischer titration and/or IR) of less than 50 ppm. As a consequence of these differences, in our previous publications, the global emission spectrum of Eu 3þ has been composed of two bands peaking at 588 nm and 610 nm, as compared to the present values of 592 nm and 615 nm and the decays have been bi-exponential, with the values t 1 ¼ 2.5 ms and t 2 ¼ 1 ms, which were ascribed to Eu 3þ surrounded by one or zero H 2 O molecules and at least one triflate anion [21] [22], a situation very different from that of the present study.…”

Luminescence Analysis of Actinides: Instrumentation, Applications, Quantification, Future Trends, and Quality Assurance

“…However, at the moment, no publication has appeared evidencing actinide luminescence in this class of solvents, most probably because of the very efficient quenching of the luminescence by the ionic liquid itself. In contrast, papers on the very intense luminescence of lanthanides in such solvents have already appeared [111], and it is expected that, by tuning the exact chemical structure of the ionic liquid, efficient actinide luminescence will be observed soon [112].…”

Understanding the Dynamics of Eu3+ Ions in Room‐Temperature Ionic Liquids – Electrochemical and Time‐Resolved Fluorescence Spectroscopy Studies

“…[14][15][16][17][18][19][20][21][22] Time-resolved fluorescence spectroscopy (TRFS) is one technique that is used extensively to understand the coordination environment of metal ions such as Eu 3+ and Cm 3+ . [23,24] Though the chemistry of trivalent lanthanides and actinides appears similar in aqueous systems, they can behave quite differently in ionic liquids. This difference can be exploited for the efficient separation of lanthanides and actinides in the reprocessing of nuclear fuels.…”

“…This difference can be exploited for the efficient separation of lanthanides and actinides in the reprocessing of nuclear fuels. [24] In view of the similarities in the chemical properties of the trivalent actinides and lanthanides, Eu 3+ ions were used as a surrogate for Am 3+ ions, and the results of the Eu 3+ fluorescence studies can be extended to the Am 3+ system. Lanthanides are produced in significant quantities by the fission of nuclear fuel.…”