CORRELATION OF MULTIPLE-SCATTERING FEATURES IN XANES SPECTRA OF AL AND SI K-EDGES TO THE AL-O-SI BOND-ANGLE IN ALUMINOSILICATE SODALITES - AN EMPIRICAL-STUDY

Using a YB66 monochromator X-ray absorption measurements were carried out at the Al K and Si K absorption edges of a series of aluminosilicate sodalites. The Al-O-Si bridging angle of the selected sodalites varies from 138 degrees to 148 degrees and the structure of the XANES with its different multiple scattering (MS) features shows a strong angular dependence. Increasing the angle results in a decrease of the MS intensities. This dependence is especially pronounced at the Al K edges which contain a couple of separated well-resolved peaks whereas the corresponding features at the Si K edges are smeared out due to a strong overlapping of the peaks.