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arXiv · 1811.10456

Spectroscopic experimental and theoretical study of Uranyl(VI) in an aqueous system - Molecular modelling meets environmental protection

Jakub Višňák·Lukáš Sobek·Nils Hoth
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Abstract

Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS) and cryo-TRLFS are sensitive tools for \textit{in situ} speciation of low-level uranium in aqueous samples, including natural waters. To tailor, often ill-conditioned (i.e., leading to ambiguous interpretations), multi-linear analysis, first-principles based theoretical computation (Molecular Dynamics and Quantum Chemistry) of luminescence spectra would be beneficial. We present a methodology to simulate TRLFS and cryo-TRLFS spectra and present vibrationally resolved luminescence spectra for aquo complex [UO$_2$(H$_2$O)$_5$]$^{2+}$(aq). Comparison to experimental data, interpretation of spectra in the terms of a minimal non-redundant set of spectroscopic parameters (peak spacing ω, the 0' $\rightarrow$ 0 peak position T$_{00}$, envelope shape parameter ΔR, average peak width σand luminescence life-times) and shifts due to ligand coordination are discussed. The minimum theory-experiment deviation in T$_{00}$ (exp. $\sim$ 20 485 cm$^{-1}$) has been reported for SORECP/TD-DFT with LB$α$ functional - 20 cm$^{-1}$, 90 cm$^{-1}$ and 100 cm$^{-1}$ for different models, a similar level of agreement has been met for ω$_{gs}$. The RMS along configuration space sampling CMD trajectory for T$_{00}$ corresponds well to σ. Preliminary predictivity study for a small set of uranyl complex species and comparison of pseudo-potential (SORECP) and all-electron results for [UO$_2$(H$_2$O)$_5$]$^{2+}$(g) are appended.

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Jakub Višňák, Lukáš Sobek, Nils Hoth. 2018-09-23. Spectroscopic experimental and theoretical study of Uranyl(VI) in an aqueous system - Molecular modelling meets environmental protection. https://arxiv.org/abs/1811.10456

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