Showing papers on "Photoemission spectroscopy published in 1980"
TL;DR: In this paper, the dispersion of the Ni band and all of the high-symmetry points in Ni band structure have been determined using angle-resolved photoelectron spectroscopy utilizing polarized synchrotron radiation.
Abstract: Angle-resolved photoelectron spectroscopy utilizing polarized synchrotron radiation has been used to determine the electronic energy states of Ni. The dispersion of the $\mathrm{sp}$ band and all of the high-symmetry points in the Ni band structure have been determined. The linewidth in the spectra from the various high-symmetry points is used to estimate the magnitude of the exchange splitting throughout the $d$ band. The measured $d$-band width is 30% smaller than predicted by calculations whereas the $\mathrm{sp}$-band width agrees within 10%. Several peaks in the photoelectron spectra which appear between 6 and 27 eV below the Fermi energy are shown to originate from multielectron excitations.
222 citations
TL;DR: In this article, the Coulomb correlation energy and the p-d gap were determined to be 4.6 ± 0.8 and 5.0 ± 1.4 eV, respectively.
178 citations
TL;DR: In this paper, the authors measured the photoelectron spectrum above 300 km for a sample of 500 AE-E orbits during the period 13 December 1975 to 24 February 1976 corresponding to solar minimum conditions.
126 citations
TL;DR: In this paper, a spectral decomposition theory is proposed to explain the physical origin of the oscillations in surface state emission intensity, which leads to the identification of additional new surface states.
Abstract: High-resolution angle-resolved photoemission spectroscopy is employed to study surface states on the Cu(111) surface, with use of synchrotron radiation in the energy range $18l~\ensuremath{\hbar}\ensuremath{\omega}l~120$ eV. The results reveal a novel periodic oscillatory behavior in surface-state emission intensity which leads to identification of additional new surface states. A spectral decomposition theory is proposed to explain the physical origin of the oscillations. It describes the measured intensity profiles and predicts that the oscillations are universal for all surface states.
122 citations
TL;DR: The HeI photoelectron spectrum of the NH2(X 2 B 1) radical produced from the rapid reaction has been recorded and three bands were observed corresponding to ionization of NH2 to the X 3 B 1, 1 A 1 and 1 B 1 states of NH 2 +.
Abstract: The HeI photoelectron spectrum of the NH2(X 2 B 1) radical produced from the rapid reaction has been recorded. Three bands were observed corresponding to ionization of NH2(X 2 B 1) to the X 3 B 1, 1 A 1 and 1 B 1 states of NH2 +. Measurement of the first two adiabatic ionization potentials of NH2 gave a value for the separation of the ground vibrational levels in NH2 +(X 3 B 1) and NH2 +(1 A 1) of 0·99 ±0·02 eV. Ionization energies of NH2 have been estimated using ab initio calculations which include the effects of electron correlation. These calculations indicate that two other bands arising from ionization of NH2, corresponding to formation of the 3 A 2 and 1 A 2 stages, should be observed in the HeI region but no clear evidence of these was obtained experimentally because of overlapping band problems. Spectra of the deuteriated radical were obtained and are consistent with these conclusions. Calculated and observed separations of the two lowest states of NH2 + are compared with those for the analogous ...
90 citations
TL;DR: In this article, the chemical bonding, extent, and evolution of metal-oxide interface regions have been probed with soft-x-ray photoemission spectroscopy following room-temperature, in situ metallization.
Abstract: The chemical bonding, extent, and evolution of metal‐oxide semiconductor interface regions have been probed with soft‐x‐ray photoemission spectroscopy following room‐temperature, in situ metallization. We identify strong atomic rearrangement and charge transfer at metal‐SiO2 interfaces. The quantitatively different processes found for Au and Al suggest new structural models. For Al‐SiO2, Al first clusters about each surface O and then grows Al2O3 by reducing SiOx (X < 2) and leaving excess Si at the interface. In contrast, Au forms islands on SiO2 with evidence of Au–Si bonding, causing an SiOx layer beneath the contact.
81 citations
TL;DR: In this paper, the electronic density of states of metallic Th and U, below as well as above the Fermi level, was investigated using X-ray photoemission spectroscopy.
Abstract: X-ray photoemission spectroscopy and bremsstrahlung isochromat spectroscopy have been used to investigate the electronic density of states of metallic Th and U, below as well as above the Fermi level. In contrast to the discrete $4f$ levels observed in the rare earths, the $5f$ states in these metals are found to be delocalized and to form relatively narrow bands. The experimental spectra are compared to recent calculations of the density of states.
64 citations
TL;DR: In this paper, the core and valence band spectra of dilute AlMn, AlNi and AlCu alloys have been investigated by x-ray induced photoemission spectroscopy (XPS).
Abstract: The core and valence band spectra of diluteAlMn,AlNi andAlCu alloys have been investigated by x-ray induced photoemission spectroscopy (XPS). The 2p levels of Mn and Cu inAlMn andAlCu change only slightly compared to their properties in the pure metals, whereas those of Ni inAlNi lose both their asymmetry and the two hole satellite. The 3s spectra of Mn inAlMn show a splitting of 2.9 eV, as compared to 4.3 eV in Mn metal. This indicates that inAlMn the Mn ion is magnetic, at least in the time scale of the XPS measurement. The valence band spectra of the alloys (and ofAlFe andAlCo) show virtual bound states with a width of about 1.5 eV and a distance relative to the Fermi energy which increases with increasingd-occupancy. The energy of the Al plasmons increase with increasingd-metal content.
58 citations
TL;DR: In this article, the He(I) photoelectron spectrum of the FO(X 2 Π i ) radical, produced from the rapid reaction has been recorded, and three bands were observed corresponding to ionization of FO (X 2Π) to the X 3 Σ-, 1Δ and 1Σ+ states of FO-.
Abstract: The He(I) photoelectron spectrum of the FO(X 2Π i ) radical, produced from the rapid reaction has been recorded. Three bands were observed corresponding to ionization of FO(X 2Π) to the X 3Σ-, 1Δ and 1Σ+ states of FO-. Analysis of the vibrational structure in each band gave estimates of , r e and D e in the corresponding ionic state.
56 citations
55 citations
TL;DR: In this article, high yield routes to the unstable halogen azides and isocyanates have permitted vacuum ultraviolet photoelectron spectra to be obtained for the chlorine and bromine azides, and the chlorine, brominine and iodine isocalates.
TL;DR: In this paper, a partial HeI photoelectron spectrum of the formyl radical has been obtained and the first adiabatic ionization potential of HCO is estimated as 8·27 ± 0·01 eV.
Abstract: A partial HeI photoelectron spectrum of the formyl radical has been obtained. In the band associated with the first ionization potential a long vibrational series was observed for both HCO and DCO and analysis of the vibrational structure, which is attributed to excitation of the deformation vibration in the ion, gave values of and 620 ± 30 cm-1 in the HCO and DCO cases respectively. For HCO the first vertical ionization potential has been measured as 9·31 ± 0·01 eV. Evidence is presented to show that the formyl radical provides an example of a rare case in photoelectron spectroscopy where the adiabatic ionization potential is not directly observed. However, with the aid of Franck-Condon calculations, the first adiabatic ionization potential of HCO is estimated as 8·27 ± 0·01 eV. Use of this value allows the heat of formation of HCO, ΔH ⦵ f(298) (HCO) and the C-H bond dissociation energy in formaldehyde to be calculated as 28·0 ± 5·4 kJ mol-1 and 354·0 ± 6·3 kJ mol-1 respectively.
TL;DR: The gas phase helium (i) photoelectron spectra of the actinide tetrahalides UF4, ThF 4, UCl 4, and ThCl 4 have been recorded as discussed by the authors.
Abstract: The gas phase helium (i) photoelectron spectra of the actinide tetrahalides UF4, ThF4, UCl4, and ThCl4 have been recorded. The spectra have been interpreted with the aid of nonrelativistic multiple‐scattering SCF‐Xα calculations and are consistent with an effective tetrahedral geometry for these molecules in the gas phase. Both the calculations and the spectra indicate that the 5f electrons in UF4 and UCl4 are essentially localized on the central metal.
TL;DR: In this paper, the photoelectron spectra of uracil, lumazine, iso-alloxazine, its 10-methyl derivative and 1,5-dihydroiso-labeled alloxazines were analyzed with the aid of earlier spectra for pyrazine, quinoxaline, o -phenylenediamine.
TL;DR: In this paper, the satellite's ionisation energy in the photo-electron spectrum of acetylene has been studied as a function of photon energy using synchrotron radiation.
TL;DR: In this article, the angular parameters for the first two vibrational states were determined over a range of photon energies from 17.7 to 31.0 eV in energy ranges where resonance absorption, accompanied by autoionization, is expected to occur.
Abstract: Angle‐resolved photoelectron spectra were taken of the first ionization state of N2 as a function of photon energy using a monochromatized beam of polarized photons from the Wisconsin Synchrotron Radiation Center. From these results the angular parameters for the first two vibrational states were determined over a range of photon energies from 17.7 to 31.0 eV. In energy ranges where resonance absorption, accompanied by autoionization, is expected to occur, β for the first excited vibrational level (v1) was frequently characterized by near zero values. In energy regions free of discrete autoionization v1 was found to have a value of β considerably larger (∼0.4 to 0.8 units) than that for the ground vibrational level (v0). This result is shown to be in accordance with recent calculations by Dehmer et al., based on the effect of vibrational motion on β in the vicinity of a shape resonance.
TL;DR: In this paper, the X-ray photoelectron spectrum of gaseous para-nitroaniline has been obtained using MgKα radiation, and it is concluded that the recent calculation of Domcke does not agree with experiment as well as was previously believed but that the main conclusion of their work about the existence of negative shake up remains a possibility.
TL;DR: In this article, electron energy-loss spectroscopy was used on vacuum-cleaved ZnSe(110) surfaces and on Ar+ bombarded-annealed surfaces of ZnTe, ZnO, CdSe, and CdTe.
Abstract: Oxidation properties of ZnSe, ZnTe, CdSe, and CdTe surfaces were studied. The following combinations of experimental techniques were used: electron‐energy‐loss spectroscopy on vacuum‐cleaved ZnSe(110) surfaces and on Ar+ bombarded‐annealed surfaces of ZnSe, ZnTe, CdSe, and CdTe. Photoemission spectroscopy also was used on a vacuum cleaved ZnTe(110) surface. The oxygen uptake is very slow with exposures to molecular oxygen. Thus oxide overlayers were prepared by an electron‐beam irradiation technique which greatly enhanced the oxygen uptakes. Changes in loss spectrum detected on oxidation of CdTe can be explained by formation of TeO2. For the case of ZnTe, the shifted Te 4d loss due to TeO2 appears at the oxygen coverage, ϑ, of about 0.5 of a monolayer, and losses characterizing formation of ZnO are seen at ϑ≳1. The oxide overlayer on ZnTe is composed of TeO2 and ZnO and, in addition, an unidentified complex oxide for the heavily oxidized surface. On further oxygen exposures and beam irridation of this oxi...
TL;DR: In this article, high-resolution X-ray photoemission spectroscopy (XPS) measurements of a variety of metallic glasses were obtained by melt spinning or splat cooling.
Abstract: High-resolution X-ray photoemission spectroscopy (XPS) measurements of a variety of metallic glasses are presented. The metallic glasses were obtained by melt spinning or splat cooling. The results are used to give an insight into the structure of the electronic states in metallic glasses.
TL;DR: In this article, X-ray photoemission spectroscopy (XPS) studies have been undertaken on a series of soda aluminosilicate glasses with Al/Na ratio varying from 0 to 1.33.
Abstract: X-ray photoemission spectroscopy (XPS) studies have been undertaken on a series of soda aluminosilicate glasses with Al/Na ratio varying from 0 to 1.33 to test the current structural models for these glasses. By monitoring the amount of bridging and nonbridging oxygens as a function of Al/Na ratio, XPS results indicate that the amount of nonbridging oxygens in the glass structure is directly proportional to the sodium concentration and independent of the Al/Na ratio, thus contradicting the expectation of all the proposed structural models. Changes in the charge distribution of the aluminosilicate glass network and the sodium ions are clearly evident in the XPS results.
TL;DR: The adsorption of pyridine on a clean Ag(110) surface was characterized with ultraviolet photoemission spectroscopy, flash desorption and Auger electron spectrographs as mentioned in this paper.
TL;DR: In this article, the interfacial electronic states associated with Al and Ga overlayers on cleaved GaAs (110) surfaces are studied by ultraviolet photoemission spectroscopy (UPS) and low energy electron diffraction (LEED).
Abstract: The interfacial electronic states associated with Al and Ga overlayers on cleaved GaAs (110) surfaces are studied by ultraviolet photoemission spectroscopy (UPS) and low energy electron diffraction (LEED). Deposition of Al or Ga can produce valence‐band spectra nearly devoid of new structure. Sb produces quite significant changes in the surface valence band and is shown as a contrasting example. Pseudopotential calculations from the literature for Al‐ and Ga‐ordered overlayers are found to be in somewhat better agreement with the data than the corresponding tight‐binding calculations, particularly in the adatom states which lie above the GaAs valence‐band maximum (VBM), although neither calculation gives a good description of the observed overlayer states. It is shown that Al and Ga most likely form two‐dimensional clusters or rafts on the surface at submonolayer coverage which are not in registry with the GaAs surface lattice. A comparison is made with results by other workers for Al, Ga, and In on GaAs ...
TL;DR: In this article, high-resolution photoelectron spectra of CS 2 have been obtained by photoionization with the He(I) (58.4 nm), Ne(I), (73.58-74.37 nm) and Ar(I, 104.8-106.7 nm) resonance lines.
TL;DR: In this paper, the occupied and empty density of states (DOS) of α-uranium and of the compounds UO2, US, and UAs were investigated using X-ray photoemission spectroscopy and BIS.
Abstract: X-ray photoemission spectroscopy (XPS) and bremsstrahlung isochromat spectroscopy (BIS) have been used to investigate the occupied and empty density of states (DOS) of α-uranium and of the compounds UO2, US, and UAs. At the photon energy (1486.6 eV) used in both methods, the l = 3 projected DOS is bringing the dominant contribution to the experimental spectra. In the pure metal, the total 5f DOS appears as a 4 eV wide band showing a splitting. A completely different situation is encountered in the insulator UO2 which contains two localized 5f electrons. Discrete XPS (5f1) and BIS (5f3) final states are observed on each side of EF, allowing the first determination of the Coulomb correlation energy for 5f electrons. In the occupied part of the band the p states are clearly separated from the 5f peak. The XPS spectra of US and UAs show similarly separated p and f structures but the metallic character of these compounds is recognized by the high DOS at EF. Their BIS spectra are formed by a dominant peak followed by an intense tail extending far above EF. This feature is attributed to strong many-body effects, as demonstrated by the line shape of the U core levels in these compounds. Satellites involving discrete excitations to empty 5f states are observed in the spectra of UO2 and Th metal.
TL;DR: In this article, a time of flight spectroscopy using pulsed synchrotron radiation is shown to provide accurate binding energies and reliable intensity measurements, taking advantage of the high transmission as well as good resolution for low kinetic energy (0-1 eV) electrons.
Abstract: Photoelectron time of flight spectroscopy using pulsed synchrotron radiation is shown to provide accurate binding energies and reliable intensity measurements. Advantage is taken of the high transmission as well as good resolution for low kinetic energy (0-1 eV) electrons, to measure the variation of vibrational branching ratios for [Math] and [Math] states of [Math] upon excitation of oxygen along selecte resonance profiles. Dramatic deviation from Franck-Condon factors are observed.
TL;DR: In this article, the authors extended Adawi's calculation of photoelectric current for noninteracting electrons to the case of a Fano resonance, which involves electron interactions, and proposed a method to calculate the Auger current that is produced by the filling of the core hole.
Abstract: Adawi's calculation of the photoelectric current for noninteracting electrons is extended to the case of a Fano resonance, which involves electron interactions. The method allows the calculation of the Auger current that is produced by the filling of the core hole. With Auger processes included, the primary photocurrent still exhibits a Fano line shape but with a value of the $q$ parameter different (always smaller) than that of the optical-absorption spectrum. The spectrum of the Auger current with respect to incident photon frequency is Lorentzian and centered at the position of the resonance. At a given frequency, the optical-absorption rate equals the sum of the primary and Auger currents.
TL;DR: In this article, the optical gap of a-sixc1-x:h films was investigated and the results of X-ray photoemission spectroscopy, infrared absorption measurements, etc., on a-Sixc1x:H were discussed.
Abstract: Hydrogenated amorphous silicon-carbon alloy (a-SixC1-x: H) films are prepared by simultaneous if reactive sputtering of silicon and graphite in a H2–Ar gas mixture. The optical gap E0 of a-SixC1-x: H depends on alloy composition x and preparation conditions. The optical gap E0 of a-SixC1-x: H prepared under a same condition is ~1.7 eV at x=1.0 (a-Si: H), increases with the decrease in x, reaches a maximum value of 2.2 eV at x=0.6 and then decreases with decrease in x, reaching ~1.4 eV at x=0 (a-C: H). For films prepared at lower substrate temperature, the optical gap becomes larger. This behavior of the optical gap is discussed referring to the results of X-ray photoemission spectroscopy, infrared absorption measurements, etc., on a-SixC1-x: H.
TL;DR: In this article, angle-resolved ultraviolet photoemission spectroscopy was used to determine the bonding orientation of CO adsorbed on the ZnO (1010) surface.