Call for a first XAFS Round Robin test

Christopher T. Chantler, Bruce A. Bunker, Hitoshi Abe, Masao Kimura, Matthew Newville and Edmund Welter

 

Round Robin tests are an established tool in analytical chemistry and related applications. The main objective of these tests is to check the comparability of analytical results among different laboratories or different analytical procedures. X-ray Absorption Fine Structure (XAFS) spectroscopy is today an analytical method used in many diverse fields of science, including industrially important applications such as catalysis and energy materials research. With XAFS beamlines in operation at almost every synchrotron radiation source worldwide it appears sensible to undertake a series of round robin tests to validate the results of XAFS experiments and to test the comparability of results gained from experiments at different laboratories.

The International X-ray Absorption Society (IXAS) and the XAFS commission of the International Union of Crystallography (IUCR) are calling for a series of Round Robin tests [1]. This call is based on the outcome of a series of workshops about data quality in XAFS spectroscopy (Q2XAFS) which were held in 2011, 2015 and 2017 (proceedings of this last workshop can be found in J. Synchrotron Rad. 25(4) July 2018) and on the experiences which were gained from a Round Robin that involved the now on-going project among XAFS beamlines in Japanese synchrotron sources. [2] The individual Round Robins will address different possible factors for deviations among spectra of the same sample measured at different beamlines or following different measurement protocols.

The present call is for the first Round Robin and identical pieces of Ti, Cu and Mo foils will be provided to all participating groups as samples. The samples are measured at the participating experimental stations following their respective standard modes of operation. Later calls will also include powdered samples and sample preparation procedures.

The main objectives of the first round robin will be to:

- Gain experience with the organisation and implementation of a round robin

- Test the catalogue of meta-data for relevance and completeness as a basis for a future XAFS spectra database.

- Search for deviations between spectra in the XANES and EXAFS regions and correlate deviations with meta data by applying established statistical tests

- Test the influence of deviations on typical EXAFS variables like bond length and coordination numbers

The results of the Round Robin will be published in a report, which will be available online via the webpages of the organising institutions. Given adequate significance of the results, a summary of the test outcome will be published in a peer reviewed journal. In both cases, the published data will not allow the identification of the sources of individual spectra. 

This round robin is targeted to all facilities able to measure EXAFS spectra in the intended energy range, including lab source based equipment. In case of questions, please contact one of the coordinators.

In case of questions or suggestions, please contact the organisers

email: xafs-rr@desy.de

[1] C. T. Chantler, B. A. Bunker, H. Abe, M. Kimura, M. Newville and E. Welter. A call for a round robin study of XAFS stability and platform dependence at synchrotron beamlines on well defined samples. J. Synchrotron Rad. 25(4), 935-943 (2018).

[2] First results were presented during the XAFS17 conference in Krakow, Poland