Molecular orbital calculation of graphite K-V X-ray emission spectra

The DV-Xa molecular orbital (MO) calculation method has been applied to the carbon K-V X-ray emission spectra of graphite. The calculated 2p density o f states (DOS) of a larger model cluster, which avoided the influence of da ngling bonds of the cluster edge, was in excellent agreement with the X-ray emission spectra, The calculated pi and a subbands of 2p DOS explained the polarized behavior of the spectra. The orientation of graphite was quantit atively discussed by means of polarization of the spectra. These results we re applied to the analysis of the structural change of mechanical milled gr aphite; the structure change of the ball-milled graphite was studied by the X-ray spectroscopy and MO calculation. It was shown that the refinement of graphite powder occurred for up to 1000 h of milling, keeping the graphite structure, and that a further milling changed the C-C bonding within the g raphite layer network. (C) 1999 Elsevier Science B.V. All rights reserved.