Extended energy-loss fine structure analysis of 3d transition metals usingL ionization edges

The extended energy-loss fine structure (EXELFS) in electron-energy-loss sp ectroscopy has been compared experimentally with the extended X-ray absorpt ion fine structure (EXAFS), for determining local structure around 3d trans ition metals. Since the EXELFS spectrum is acquired in an analytical transm ission electron microscope, the probing beam can be focused to offer a late ral spatial resolution in the nanometre range, which is several orders of m agnitude better than that of X-rays. Also, the microscope allows the area o f interest to be imaged and analysed by other methods. However, difficultie s in the analysis of EXELFS of 3d transition metals arise from the overlap of the edges in the accessible L series. EXELFS of L ionization edges of cr ystalline Ni and Cu were examined as test specimens. The overlapped L-1, L- 2 and L-3 edges were separated and compared with the K-edge EXAFS of the sa me samples. The first- and second-nearest-neighbour distances from EXELFS a re in agreement with those measured from EXAFS and X-ray diffraction. As a structural probe, however, the accuracy of quantitative analysis of EXAFS i s still superior since the L-edge EXELFS decays more rapidly than K-edge EX AFS.