The Al L2 3 spectrum for dilute alloys of Al in Mg, and the Mg L satellite spectrum produced by transitions in atoms with doubly ionized 2p core levels have been measured. The two spectra contain similar features associated with screening of the extra core hole, but are otherwise dissimilar, which suggests that the equivalent-core approximation is not valid. The threshold peak is broadened in both spectra. The Al-impurity spectrum is found to be about 1 eV wider than that of the Mg host. The L3-L, intercore transition in doubly ionized Mg is observed. Finally, a second, weak, high-energy satellite of Mg is observed that may be produced by transitions from the 'So state of the doubly ionized core levels. These results provide important new data for comparison with theories of the electronic states of impurity atoms in metals.
The L2,3 soft x-ray emission (SXE) spectra of Al in metallic Al, Al-Mn alloys, dilute Al-Mg alloys, the intermetallic compounds LiAl and Ni3Al, the semiconducting alloy (Al-Ga)As and insulating Al2O3 are presented. The spectra provide a measure of the s-like partial density of states (PDOS) localized at the Al atoms and show prominant qualitative features that may be identified with each of the major types of bonding in solids, ie. metallic, covalent and ionic. The spectra of metallic Al and of the Al-Mn alloys have parabolic densities of states characteristic of nearly free electron PDOS's. Al in Mg alloys have metallic PDOS's with a strong enhancement of the low energy region of the spectrum which is associated with screening of the extra charge on the Al ion core. In LiAl, the Al has tetragonal local symmetry, the spectrum is similar to that of silicon and the bonding is a combination of covalent and metallic. In AlxGa1-x As alloys, the Al has tetragonal local symmety, but the spectrum is strongly modified from the characteristic covalent form by the presence of a strong ionic component in the bonding. Finally, the spectrum of Al2O3 shows features characteristic of localized electronic orbitals and ionic bonding
%e present e-beamcxcited soft-x-ray emission spectra and total-photoelectron-yield spectra in the 20-600 eV photon energy range for Ba2YCu307-. In soft-x-ray emission, the N&, 5 structure of Ba, the M&, 5 spectrum of Y, and the E spectrum of 0 provide a direct measure of the p-type partia1 density of states (p-PDOS) localized on the respective atomic sites. In each case the p-PDOS is very small at the Fermi energy sF. The maximum in the 0 EC spectrum is 2.6 O. S eV belo~sF. This result provides direct confi.rmation that the shoulder previously found at sF-2.3 eV in photoelectron emission spectra is associated with 0 p orbitals. No changes are observed between spectra taken above and belo~T,.
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