Zn K edge and O K edge x-ray absorption spectra of ZnO surfaces: implications fornanorods

Abstract

Zn K edge and O K edge x-ray absorption near-edge structure (XANES) spectraof ZnO surfaces are calculated. The difference between theoretical XANES forZnO surfaces and ZnO bulk is then compared to the earlier observed differencesbetween experimental XANES for ZnO nanostructures and ZnO bulk as taken fromthe literature. It follows from our calculations that the differences between theexperimental XANES of bulk ZnO and nanocrystalline ZnO is not due to theenhanced role of the surfaces in nanostructures. Rather, the difference in XANEShas to reflect differences in the local geometry around the photoabsorbing sites.The dependence of XANES of ZnO surfaces on the polarization of the incomingradiation is also investigated theoretically and found to be similar as in the bulk.