X-RAY-ABSORPTION NEAR-EDGE STRUCTURE OF TRANSITION-METAL ZINCBLENDE SEMICONDUCTORS - CALCULATION VERSUS EXPERIMENTAL-DATA AND THE PRE-EDGE FEATURE

X-ray-absorption near-edge structure (XANES) data were collected for Zn in sphalerite (ZnS), and for Cu and Fe in chalcopyrite (CuFeS2), where all three cations are in nearly identical coordination environments. The data have similar features, except near the edge, where the edge maximum decreases in amplitude, while a pre-edge feature appears and increases in amplitude from Zn to Cu to Fe. The pre-edge feature was previously assigned to a 1s-to-3d atomic transition for Cu and Fe in the chalcopyrite structure. XANES calculations were performed for all three edges. The multiple- and single-scattering contributions to the calculated edge spectra were scaled down to better fit the experimental data. The conclusions from the calculations indicate that the pre-edge feature in the experimental Cu- and Fe-edge data for chalcopyrite can be due to interference effects from the atomic structure surrounding the absorber, but cannot exclude the possibility that the pre-edge feature is due to atomic bound-state transitions of the absorber.