A web-based library of XAFS data on model compounds

With the predominance of XAFS analysis for structural information now using theoretical standards such as FEF~ (Zabinsky et al., 1995), one might question the utility and need for of an archive of XAFS data.The motivation for this work is threefold.First, the library is intended to reduce the need to collect XAFS data on model compounds, which is still useful in assessing the reliability of theoretical XAFS standards, and for empirically determining reasonable fitting parameters such as Eo and So 2. Due to differences in beamline characteristics, this need will not be completely eliminated, but it is expected that having data easily accessible will be more efficient and convenient than re-measuring model compounds for most users.Second, the data in the library serves as a basis set for empirical XANES analysis, either using edge shifts and peak heights or more elaborate analysis methods based on combinations of spectra (Wasserman, 1997).Third, the library provid¢~ data that can be used as test cases for comparisons to theoretical XANES calculations, which are not currently adequate for quantitative analysis.An archive of XAFS data collected on standard model compounds of transition metals has been constructed and made available by the world wide web.The data in this library have all been taken in transmission on powder samples free of thickness effects.Data are stored in individual files in a standardized ASCII column format.Fields describing the contents of files can be searched easily.The data are intended to provide standards for comparison of EXAFS analysis procedures, for empirical analysis of XANES features, and to test theoretical XANES calculations.Emphasis has been placed on inorganic transition metal compounds to assist the analysis of environmentally relevant~samples.