Core-hole effects in the EELS spectra of the B K-edge in Aluminium- and Titanium diboride

摘要

We report the orientation dependent B K-ELNES spectra of the isostructural compounds AlB_2 and TiB_2. The orientation dependence is rationalized in terms of the anisotropic nature of the common crystal structure. We ascribe the origin of the discrepancies between the broadened ground state DOS and experiment to the presence of a core hole in the final state. The core hole effect is selfconsitently accounted for via the use of ab initio supercell calculations, leading to improved agreement with experiment particular in certain crystallographic directions where screening of the core hole is expected to be much reduced.