ANALYSIS OF EXAFS DATA FROM MIXED-SHELL SYSTEMS

A new method for analysis of EXAFS data from coordination shells conta ining two types of atoms distributed at two well defined distances is proposed. The method, which in effect isolates the individual contribu tions of the two subshells, can be viewed as a refinement of conventio nal techniques such as beat analysis and multi-shell least-squares fit ting. No external information on the structure of any of the contribut ing subshells is required beyond the usual assumption of small or 'Gau ssian' disorder. As much as fivefold reduction in the confidence limit s of the coordination numbers in comparison with unrestricted multi-sh ell fits is demonstrated. The range of applicability and limitations o f the method are discussed in detail.