International Workshop on
Advanced Techniques in Actinide Spectroscopy 2014 (ATAS 2014)03.–07.11.2014, Helmholtz-Zentrum Dresden-Rossendorf e.V., Germany
Round-Robin Test in actinide spectroscopy
The inter-laboratory test aims at a unique comparison of molecular information obtained from the different spectroscopic (TRLFS, vibrational spectroscopy, EXAFS, NMR, ESI-MS) and theoretical methods. Hence, concordance as well as the source of discrepancies between the several methods will be evaluated. Hopefully, this illuminates the potential, together with the limitations of coupling different spectroscopic and theoretical approaches as tools for the molecular study of actinide complexes. The test is understood to stimulate scientific discussion, but not as a competitive exercise between the labs of our community. The general procedure as well as the time schedule is given here.
The main goal of this test (RRT) is the comprehensive molecular analysis of the actinide complex system U(VI)/acetate in aqueous solution independently investigated by different spectroscopic and theoretical techniques applied by leading laboratories in geochemical research.
The main levels of operation can be summarized as follows:
- Data generation:
Samples provided by HZDR are measured by the respective technique(s) in the participating labs.
- Data processing and structural interpretation:
Raw data are treated by the experimentalists in a reproducible way and the results obtained are interpreted by the experimentalists and structural information is derived as far as possible.
- Intra-methodology comparison of results:
Collection and summary of data obtained by a distinct technique (applied in different labs) by a speaker of cluster (to be nominated) and discussion within the cluster.
- Inter-methodology comparison of results:
Presentation of the results of each cluster and general discussion of RRT’s outcome at ATAS 2014.
A detailed schedule of the RRT is depicted in Figure 1. The material (and experience) collected during this exercise certainly generates a large pool for further activities. Thus, the list given below provides more details of the RRT’s workflow and reaches beyond the next twelve months – to which degree is still a matter of discussion and mutual agreement.
Comparison of data obtained by a distinct technique (applied in different labs), here the speaker of each cluster (in consensus with all participants) may restrict further experimental details to homogenize approaches as far as sensible:
- Definition of what is considered as raw data (interferograms, single beam spectra, ...) and which references (if applicable) are recommended (e.g. metal foils for XAS or internal NMR standards).
- Reproducibility of raw data as defined above
- Comparability of “primary” data evaluation: base-line correction, smoothing, normalization, averaging, deconvolution,… (depending on technique)
Interpretation of experimental data with respect to physico-chemical properties (system characteristics and/or properties of individual components)
- Identification of system complexity (number – and sometimes type – of significant components)
- Quantitative evaluation of data: peak positions, lifetimes, intensities (relative or absolute), band shifts, energies, ... (depending on technique)
- Determination of component characteristics: redox states, stoichiometry, structure (bond lengths, denticities, shell populations incl. hydration)
Intercomparison of information obtained by different techniques
- Potentials and limitations as well as complementarities
- Information from coupling of different spectroscopic and theoretical approaches, iterative data processing if applicable (e.g. based on intermediate results from a complementary technique)
- Evaluation of the inter-laboratory test and identifying applications towards more complex scientific questions (i.e. planning future extensions – experimental and/or re-evaluation of the data already collected). Namely, this may include a redistribution of raw data within a cluster for analyses by different operators according to their procedures.
At this stage, clearly items 1 and 2 are in the focus, but we are confident that also the other aims will be addressed at least partially. Hopefully, items 3 and 4 will be discussed intensely at ATAS workshop.
Notice: The test does not aim at a competition of different labs, showing which one has a better instrumental set-up.
Fig. 1: General procedure and expected discussion topics
If you are interested in partcipation, please do not hesitate to contact us: ATAS@hzdr.de!