2018/09/23 by Jakub Višňák, Višňák, Jakub, Lukáš Sobek +3
Chemistry · Chemical Engineering · #Radioactive element chemistry and processing #Analytical chemistry methods development #Chemical and Physical Properties in Aqueous Solutions
paper · pdf · doi:10.48550/arxiv.1811.10456
Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS) and cryo-TRLFS are sensitive tools for 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 [UO2(H2O)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' → 0 peak position T00, 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 T00 (exp. ∼ 20 485 cm-1) has been reported for SORECP/TD-DFT with LBα functional - 20 cm-1, 90 cm-1 and 100 cm-1 for different models, a similar level of agreement has been met for ωgs. The RMS along configuration space sampling CMD trajectory for T00 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 [UO2(H2O)5]2+(g) are appended.