Abstract
Arsenic K-edge X-ray absorption near-edge structure (XANES) spectroscopy has been used to investigate the local geometry around the pnictogen site in the REFeAsO (RE=La, Pr, Nd and Sm) oxypnictides, combined with full multiple-scattering calculations to understand different XANES features. The As K-edge XANES spectrum for the LaFeAsO is found to be significantly different from the other oxypnictides. The results suggest that interlayer order/disorder has a significant effect on the XANES features with the coupling between the FeAs and the REO spacers being important in the electronic and magnetic properties of the oxypnictides.