On the interpretation of valence band photoemission spectra of NiO

The valence band photoemission spectrum and the L₃VV Auger spectrum of NiO are compared. The satellite found in the valence band of NiO and other Ni compounds is interpreted as an unscreened 3d⁷ final state, whereas the main d-emission is a 3d⁷ final state screened by a d electron in an exitonic state.     

Strength of plasmon satellites in the valence band photoemission spectra of metals

The strength of the first bulk plasmon satellite in the valence band photo-emission spectra of simple metals has been calculated for the dispersionless plasmon model. It is found that due to the mobility of the final state hole in the valence band, the strength of the plasmon satellite is lowered compared to that of the core state. This conclusion is qualitatively confirmed by an independent experiment of Van Attekum and Trooster.     

On the valence band photoemission of highT c superconductors

The valence band photoemission spectrum of highT _c -superconductors is discussed based on the half-filled single band Hubbard Hamiltonian with the strong Coulomb interaction. We discuss how to analyze these valence band and deep core level excitation spectra, concerning particularly with which orbital, Cud or Op state, a hole will occupy in the CuO₂ plane.     

GaSe valence band structure from angle-resolved photoemission spectroscopy

Energy-wavevector dispersion curves for the GaSe valence bands obtained from angle-resolved photoemission spectra are compared with pseudopotential band calculations. It is found that the third density-of-states feature below the top of the valence bands (peak C) is related to the Ga-Se bond rather than the Ga-Ga bond. A peak not appearing in the angle-integrated spectra appears as the most intense feature at normal emission, and helps to identify completely the nature of the valence bands down to 7–8 eV below the Fermi energy.     

Giant enhancement of the valence band photoemission intensity in γ-Ce

We have observed a giant enhancement of the Ce valence band emission above the 4d absorption threshold. It is interpreted as being due to autoionization decay following 4d¹⁰4f¹ → 4d⁹4f² transitions. By taking advantage of this effect we have been able to make a determination of the location of the 4f levels in γ-Ce.     

Surface and bulk valence band photoemission of silicon carbide

Surface and bulk valence band photoemission spectra have been obtained for silicon carbide using Zr M-zeta (151.4eV) and Mg Kα_1,2 (1253.6eV) excitation, respectively. The data have been corrected for various broadening effects using a deconvolution procedure. Spectra for single-crystal hexagonal α-SiC and for epitaxial films of cubic β-SiC on Si (1 0 0) are compared with the results of band structure calculations. Differences in the spectra for various surface reconstructions suggest the existence of surface resonances, but no surface states are observed in the bulk optical bandgap.     

The XPS valence band spectra of NbC

The x-ray photoemission valence band spectra of NbC have been measured and are compared with the x-ray emission spectra and with the results from band structure calculations. This comparison leads to a large enhancement of theC2 _p photoabsorption cross section (at=1,487 eV) compared to the value calculated for the free atom. The effect of the nonmetal vacancy in the valence band can be described very well with vacancy cluster calculations.     

Recent studies of valence band emission spectra

The paper will discuss recent experimental studies of intensity distribution in the K emission bands of the light metals Li and Be and also in the M_2,3 emission spectra of the 3d metals. Consideration will be given to problems dealing with excitation, detection and reduction of data. Factors which might modify and distort the band shape will also be discussed. In this category fall the effect of self-absorption in the target, the contribution from the underlying continuum, the overlap of individual bands, intensity anomalies arising from Auger processes, the width of inner levels and the presence of high and low energy tails. The influence of such instrumental features as the spectral response of the monochromator, modifications produced by the grating, and the effect of contaminants will also be assessed. Where possible, the observed features of the bands will be discussed in the light of recent calculations dealing with band widths and density of states.     

Surface charging effects on valence band spectra in X-ray photoemission: Crystalline and Amorphous As2S3

In X-ray photoemission (XPS) studies on insulators, strong electric fields associated with surface charging can perturb the observed spectra. We find that the standard technique of flooding with thermal electrons to neutralize the net charge does not eliminate this effect for valence band spectra, but that the use of thin or (for photoconductors) illuminated samples does solve the problem. These conclusions are demonstrated by experiments revealing new structure in, and real differences between, the XPS valence band spectra of crystalline and amorphous As₂S₃.     

Internal X-ray photoemission in aluminum: Excitation of electrons from the valence band

Measurements are reported of Al valence-electron excitation by Ka_1,2 X-rays internally generated in evaporated specimens by electron bombardment. The X-ray photoelectron energy distribution is consistent with the u.v. distribution of Huen and Wooten. Weak structures are found in the energy distribution at positions corresponding to those in the calculated density of states.     

Adsorption effects on the high resolution valence band photoelectron spectra of zinc and cadmium

Photoelectron spectroscopy with 40.81 eV photons has been used to determine accurately the binding energies and spin-orbit splittings of the metallic Zn 3d and Cd 4d electrons. The spin-orbit splittings were found to be 0.65(4) eV and 1.00(5) eV respectively, in good agreement with previously obtained values. The resolution of the doublets was enhanced by deconvolution procedures using an experimentally determined spectrometer line-shape. Clean surfaces of the metals were prepared by mechanical scraping in situ, and the activation energies for adsorption of residual gases on these surfaces have been determined.     

The valence band of some light rare-earth metals studied by photoemission spectroscopy

The valence bands of La, Ce, Pr, and Nd have been studied by ultraviolet photoelectron spectroscopy (UPS) (He II, hv=40.8 eV) and compared to results from X-ray photoelectron spectroscopy (XPS)(Mg Kα_{1, 2}). The energy positions of the $\text{4?}$ levels are in good agreement with earlier XPS results and calculations based on estimates from optical and thermodynamic data. The widths of the sd bands and the $\text{4?}$ levels and the relative emission intensities are discussed.     

Detailed x-ray photoemission study of the valence band of Cu,Ag and Au

Detailed X-ray photoemission studies (hv = 1253.6 eV) of the valence band structure of the noble metals Cu, Ag and Au are reported. The experimental results are compared to ultraviolet-photoemission measurements and theoretical calculation of the band density of states.     

Calculation of photoemission characteristics for a semiconductor model with s-like valence band and p-like conduction band

The dependence of the quantum yield and photocurrent density on Light frequency is theoretically studied for various orientations of the emission surface for the semiconductor model with simple cubic lattice and s-like valence band and p-like conduction band, and it is assumed that electron photoexcitation occurs due to indirect optical transitions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 100–104, August, 1977.     

Polarization effects in the photoemission spectra of trigonal tellurium

Strong and unequivocal polarization effects are observed on the photoemission spectra of vacuum-cleaved, $\text{(10}\text{1}\text{0)}$ Tellurium. Calculations of the energy distribution curves of the photoelectrons have been performed based on pseudopotential band structure and wave functions. The results correlate with the observations and allow for the interpretation of the measured EDC in terms of bulk properties and surface effects.