F.R. McFeely

The electronic structure of SrTiO3 and some simple related oxides (MgO, Al2O3, SrO, TiO2)☆

Abstract The valence band density of states (VBDOS) of the insulating oxides SrTiO 3 , TiO 2 , SrO, MgO and Al 2 O 3 obtained by X-ray photoelectron spectroscopy (XPS), are reported. Qualitatively, the VBDOS of these oxides are similar to one another. The XPS results are compared with results from soft X-ray emission spectroscopy (XES), ultraviolet photoemission spectroscopy (UPS), and theoretical calculations. There are some differences (in particular for TiO 2 ) between the XES and XPS results, which are probably due to matrix element effects enhancing different features of the VBDOS in the two techniques. The XPS results definitively establish the position of the O 2 s level, which had been erroneously assigned in previous low-energy UPS measurements. Cluster-type calculations are demonstrated to give a reasonable representation of the VBDOS for the oxides.

Characteristic energy loss structure of solids from x-ray photoemission spectra

Abstract Energy loss peaks in x-ray photoemission spectra of nine metals are presented. No strong evidence for intrinsic plasmon structure was observed. Spectra from the free electron-like metals, Al, Li, and Na under ultra-high vacuum (10 −11 torr) conditions show intense bulk plasmons and surface plasmons. Systematic variations in the characteristic energy losses are reported for the series Ag to Te. In addition to losses that may be attributed to plasma oscillations of the 5s5p bands, with N = 1 and 2 electrons, respectively, both Ag and Cd show additional high-energy losses that may arise through 4d-shell participation, with N = 11 and 12.

X-ray photoemission spectra of the 4d levels in rare-earth metals

Abstract High resolution photoemission spectra of the 4d levels in the rare-earth metals are reported. The metals with partially filled 4f shells display very complicated structure due to multiplet splitting, while those with the 4f 0 or 4f 14 configuration exhibit only spin-orbital splitting. A detailed analysis is given for the 4f 7 metals europium and gadolinium.

Evidence for a localized magnetic moment in paramagnetic α-Mn from multiplet splitting

Abstract High resolution X-ray photoemission spectra of paramagnetic α-Mn are reported. The 3 s and 2 s levels show considerable multiplet splitting. Analysis of the 3 s splitting yields a spin S ∼ 1.25, implying a magnetic moment of 2.5 μ B , in excellent agreement with a recent susceptibility value, but larger than the neutron scattering result.

An ionicity scale based on x‐ray photoemission valence‐band spectra of ANB8−N and ANB10−N type crystals

A quantitative scale of ionicity based on x‐ray photoemission studies of the valence‐band density of states of many ANB8−N and ANB10−N crystals is discussed. The scale is empirical. It involves allocating the energy splitting of the two most tightly bound valence‐band peaks between covalent and ionic contributions. Several ternary alloys and chalcopyrite‐type crystals were also included in this study. The scale was found to be superior to the molecular orbital approach of Coulson and the thermochemical scale of Pauling because of the symmetrical treatment of covalent and ionic contributions. It appears to have wider applicability than the Phillips‐Van Vechten scale. The strengths and weaknesses of the proposed scale are discussed.

Multiplet splittings of the 4s and 5s core levels in the rare earth metals

Abstract The multiplet splittings of the 4s and 5s levels in the rare earth metal series La through Lu are reported and discussed.

An X-ray photoemission investigation of the density of states of β′ -NiAl☆

Abstract The electronic structure of β′ -NiAl was studied by X-ray photoemission spectroscopy (XPS). The observed valence band density of states agrees quite well with the non-relativistic APW calculations of Connolly and Johnson. These results are also compared with other experimental data. The hypothesis of d -band filling is supported by our XPS measurements.

X-ray photoemission study of Gd, Tb and Dy 4f and valence bands☆

Abstract High-resolution XPS spectra of 4f electrons further support trivalent ion-core assignments for Gd, Tb and Dy, but the valence-band spectra vary considerably.

A high-resolution X-ray photoemission study of the total valence-band densities of states of GaSe and BiI3

Abstract The total valence band denstiy of states spectra for the semiconducting layered compounds GaSe and BiI3 were obtained by X-ray photoemission spectroscopy. The results for GaSe were used to test recent band structure calculations and are compared with earlier photoemission results. The BiI3 data are the first experimental determination of the total valence band density of states for this compound. Since no calculations exist for BiI3, tentative assignments were made.

The effect of spin-orbit splitting on the valence band density of states of lead

Abstract Tight-binding calculations are reported for the valence bands of lead, with and without spin-orbit splitting in the 6p bands. The addition of spin-orbit interaction is necessary to reproduce the two-peaked structure in the 6p density of states observed in X-ray photoemission, in contrast to the assertion by Breeze that crystal-field effects alone are enough. The observed splitting is, however, only fortuitously nearly equal to the atomic spin-orbit splitting. The tight-binding band structure, with spin-orbit splitting, gives better overall agreement with optical, Fermi surface, and photoemission data than did any of the three earlier band structures.