Open AccessThe influence of experimental and model uncertainties on EXAFS results
Author(s) -
Rossner Hermann,
Krappe Hans
Publication year - 2001
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049500015004
Subject(s) - a priori and a posteriori , truncation (statistics) , radius , scattering , computational physics , skewness , parameter space , background subtraction , statistical physics , physics , series (stratigraphy) , mathematics , statistics , optics , computer science , philosophy , pixel , computer security , epistemology , paleontology , biology
We analyze EXAFS oscillations in k‐space with the FEFF code to obtain main‐shell distances R ν and mean‐square displacement parameters σ i 2 for all single and multiple scattering paths i in the shells ν up to a maximum shell radius R max . To quantify the uncertainty in the determination of these model parameters we take into account experimental errors and uncertainties connected with background subtraction, with the approximate handling of the electronic many‐body problem in FEFF, and with the truncation of the multiple scattering series. The impact of these uncertainties on the R ν and σ i 2 is investigated in the framework of Bayesian methods. We introduce an a priori guess of these model parameters and consider two alternative strategies to control the weight of the a priori input relative to that of the experimental data. We can take a model parameter space of up to 250 dimensions. Optionally we can also fit the coordination numbers N j (j≤ν) and the skewness of the distribution of the R ν besides the R ν and σ i 2 . The method is applied to 10K Cu K‐edge and 300K Au L 3 ‐edge data to obtain model parameters and their a posteriori error correlation matrices.