PNNL

Abstract

A comprehensive molecular analysis of a simple aqueous 51 complexing system?U(VI) acetate?selected to be independently inves- 52 tigated by various spectroscopic (vibrational, luminescence, X-ray absorption, 53 and nuclear magnetic resonance spectroscopy) and quantum chemical 54 methods was achieved by an international round-robin test (RRT). Twenty 55 laboratories from six different countries with a focus on actinide or 56 geochemical research participated and contributed to this scientific endeavor. 57 The outcomes of this RRT were considered on two levels of complexity: first, 58 within each technical discipline, conformities as well as discrepancies of the 59 results and their sources were evaluated. The raw data from the different experimental approaches were found to be generally 60 consistent. In particular, for complex setups such as accelerator-based X-ray absorption spectroscopy, the agreement between 61 the raw data was high. By contrast, luminescence spectroscopic data turned out to be strongly related to the chosen acquisition 62 parameters. Second, the potentials and limitations of coupling various spectroscopic and theoretical approaches for the 63 comprehensive study of actinide molecule complexes were assessed. Previous spectroscopic data from the literature were revised 64 and the benchmark data on the U(VI) acetate system provided an unambiguous molecular interpretation based on the 65 correlation of spectroscopic and theoretical results. The multimethodologic approach and the conclusions drawn address not 66 only important aspects of actinide spectroscopy but particularly general aspects of modern molecular analytical chemistry.