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The electronic structure of the insulator lithium amide (LiNH2), which is a lightweight complex hydride being considered as a high-capacity hydrogen storage material, is investigated by N is soft x-ray emission spectroscopy (XES) and absorption spectroscopy (XAS). The XES and XAS spectra show a band gap between the valence and conduction bands. The valence band in the XES spectrum consists of three peaks, which extend up to ~-8 eV from the valence band top. The band calculation within the local-density approximation (LDA) for LiNH2 shows energetically separated three peaks in the occupied N 2p partial density of states (pDOS) and the band gap. The energy distribution of three peaks in the XES spectrum agrees with that in the calculated pDOS except for the peak at the highest binding energy, which is attributed to the strongly hybridized state between N 2p and H is. The XES experiment has clarified that the strongly hybridized state with H is in LiNH2is located at binding energy higher than that of the LDA calculation, while the overall feature of the electronic structure of LiNH2experimentally obtained by XES and XAS is consistent with the calculated result. [ABSTRACT FROM AUTHOR]

Abstract: We have constructed a high-resolution synchrotron-radiation photoemission spectrometer combined with a laser molecular-beam epitaxy (laser MBE) thin film growth system in order to investigate the electronic structure of oxide and nitride thin films. The system was installed at the newly built soft X-ray undulator beamline BL17SU of SPring-8. Total energy resolution of 102 meV was achieved at photon energy of 870 eV. The photoemission apparatus is connected to a laser MBE chamber through a preparation chamber. Single crystal thin-film samples fabricated by laser MBE can be transferred quickly into the photoemission chamber without breaking ultrahigh vacuum. Various new studies are possible using this system and third-generation soft X-ray synchrotron light source, such as direct observation of the bulk electronic band structure of single-crystal films with no cleavable plane, the interface electronic structure of oxide or nitride heterostructures, etc. [Copyright &y& Elsevier]

Abstract: We have studied vanadium oxides corresponding to formally (), (), and () configurations and compare them with mixed valent , using hard X-ray core level photoemission spectroscopy (PES), which enables to probe bulk electronic states due to large escape depth of high kinetic energy photoelectrons. The quasi-one-dimensional mixed-valence compound and three-dimensional undergo metal–insulator (MI) transition at = 135 and 160 K, respectively. The observed V core level spectra of and show a single peak with chemical shifts corresponding to the and , while two components ( and ) are observed in . Metallic shows a bulk character additional peak at low binding energy in the V core levels. We also study the V core level spectra of these compounds, which are possible only using hard X-rays and confirm the systematics in valence states of vanadium oxides. The temperature dependence of the low binding energy peak in V spectra across the MI transition in suggests an additional screening channel available in the Mott–Hubbard correlated metal phase. [Copyright &y& Elsevier]

Abstract: Magnetic properties of a spin-glass Al40Mn25Fe15Ge20 decagonal quasicrystal (QC) have been studied by means of soft X-ray magnetic circular dichroism (MCD). Element specific magnetic hysteresis (ESMH) loops have been measured as magnetic field dependence of MCD intensity at the Mn and Fe L3-edges. A significant difference has been found in the ESMH loops between Mn and Fe in the QC, where only the Mn loop has an obvious remanent-like magnetization. This result of ESMH has suggested that Mn and Fe magnetic moments have different magnetic viscosities in the spin-glass QC. A ferromagnetic approximant-crystalline Al40Mn40Ge20 has also been investigated in comparison with the QC. [Copyright &y& Elsevier]

Abstract: In order to clarify the intrinsic bulk electronic structure of La1−xSrxMnO3 (LSMO) thin films, we have performed high-energy ( keV) synchrotron photoemission spectroscopy (PES) of Mn 2p core-levels. In sharp contrast with the previous soft X-ray PES (–1486.6 eV), the high-energy PES spectra exhibit a clear additional peak at the low binding-energy side of the Mn 2 peak. To check for surface sensitivity, we measured take-off-angle dependence of Mn 2p core-levels. The results indicate that this additional peak originates from the bulk electronic structure. The peak shows a noticeable increase in the metallic phase of LSMO for and 0.4, indicating that the origin of this peak is strongly related to the metallic physical properties of LSMO thin films. A single ion () cluster calculation including charge transfer from doping-induced states reproduces the new bulk-derived feature observed in Mn 2p core-levels. [Copyright &y& Elsevier]

Abstract: We study the bulk electronic structure of NaCoO.yHO using Hard X-ray (HX, h = 5.95KeV) synchrotron photoelectron spectroscopy (PES). The Co core level spectra show well-separated Co and Co ions. Cluster calculations suggest low spin Co and Co character, and a moderate on-site Coulomb correlation energy U3–5.5eV. Photon-dependent valence band PES identifies Co and O derived states, in near agreement with band structure calculations. We discuss the importance of HX-PES for studying correlated transition metal oxides. [Copyright &y& Elsevier]

Si 2p and N 1s spectra arising from a oxynitride film formed on Si(1 0 0) surface were measured in the photon energy range from 556 to 1471 eV, where the electron escape depth in SiO2 changes from 1.68 to 3.80 nm. It was found for the first time that the photon energy dependence of N 1s and Si 2p photoelectron spectra can be nearly reproduced if the depth profile of nitrogen atoms is known. [Copyright &y& Elsevier]

The chemical and electronic structures of SiO2/Si(1 1 1) and SiO2/Si(1 0 0) interfacial transition layers are reviewed. It will be shown, considering the penetration of electronic states from the Si substrate into SiO2 in the analysis of the thickness dependence of the energy loss of O 1s photoelectrons measured with a probing depth of 0.41 nm, that energy barriers for valence electrons, which are almost comparable to those found in SiO2, were formed when the oxide layer formed on Si(1 1 1) and Si(1 0 0) was thicker than 0.61 and 0.51 nm, respectively. In other words, the SiO2/Si(1 1 1) and SiO2/Si(1 0 0) interface defined with electronic band structure exists, respectively, in the oxide located effectively 0.61 and 0.51 nm away from the nominal interface defined with the atomic structure. In other words, incorporation of one atomic layer of oxygen at the interface does not form an electronic barrier. The extreme uniformity of the oxide layer formed on Si(1 0 0) was verified using synchrotron radiation excited high resolution XPS. [Copyright &y& Elsevier]

Abstract: In order to clarify the intrinsic bulk electronic structure of strongly-correlated electron systems, we have realized hard X-ray photoemission spectroscopy with high energy-resolution at BL29XUL in SPring-8. The total energy resolution of 75meV was achieved at the excitation energy of 5.95keV. Large probing depth of about 100Å enables us to probe intrinsic bulk electronic structure free from surface condition. The importance and capability of this technique are demonstrated by the drastic difference in the Cu 2p core-level spectra of crystals obtained using soft and hard X-rays. [Copyright &y& Elsevier]