ArcAdiA

Valence-band electronic structure of V2O3: identification of V and O bands

Wed, 30 Sep 2009 22:00:00 GMT

Valence-band electronic structure of V2O3: identification of V and O bands Papalazarou, E.; Gatti, Matteo; Marsi, M.; Brouet, V.; Iori, F.; Reining, Lucia; Annese, E.; Vobornik, I.; Offi, Francesco; Fondacaro, Andrea; Huotari, S.; Lacovig, P.; Tjernberg, O.; Brookes, N. B.; Sacchi, M.; Metcalf, P.; Panaccione, G. 2009-10 Physical Review B 80 155115 We present a comprehensive study of the photon energy dependence of the valence band photoemission yield in the prototype Mott-Hubbard oxide V2O3. The analysis of our experimental results, covering an extended photon energy range (20-6000 eV) and combined with GW calculations, allows us to identify the nature of the orbitals contributing to the total spectral weight at different binding energies, and in particular to locate the V 4s states at about 8 eV binding energy. From this comparative analysis, we conclude that the intensity of the quasiparticle photoemission peak, observed close to the Fermi level in the paramagnetic metallic phase upon increasing photon energy, does not have a significant correlation with the intensity variation in the O 2p and V 3d yield, thus, confirming that bulk sensitivity is an essential requirement for the detection of this coherent low-energy excitation.

M3M45M45 Auger lineshape measured from the Cu(111) surface: Multiplet term selectivity in angle-resolved Auger-photoelectron coincidence spectroscopy

Sat, 31 Jan 2009 23:00:00 GMT

M3M45M45 Auger lineshape measured from the Cu(111) surface: Multiplet term selectivity in angle-resolved Auger-photoelectron coincidence spectroscopy Gotter, R.; Da Pieve, F.; Offi, Francesco; Ruocco, Alessandro; Verdini, A.; Yao, H.; Bartynski, R.; Stefani, Giovanni 2009-02 Physical Review B 79 075108 The capability of the recently observed dichroic effect inangle-resolved Auger-photoelectron coincidence spectroscopy (DEAR-APECS) to disentangle individual multiplet terms has been exploited to study the lineshape of the M3M45M45 Auger spectrum measured in coincidence with the 3p(3/2) photoelectrons from theCu(111) surface. The relevant multiplet structure of the two hole final state is determined with an unprecedented sensitivity, including are liable experimental estimation of the energy of the D-1 multipletterm. Spectroscopic data for the 3p photoemission feature are also given and energy conservation applied to the photoelectron-Auger-electron pair has been successfully used in orderto quantitatively explain energy shifts in coincidence spectra. Multiple-scattering calculations prove that the DEAR-APECS effect is not destroyed by diffraction effects and a simple model which combines atomic angular distributions and electron-diffraction modulations is provided in order to obtain a detailed understanding of the multiplet energy and intensity distributions in Auger spectra.

A study of core and valence levels in beta-PbO2 by hard X-ray photoemission

Wed, 31 Dec 2008 23:00:00 GMT

A study of core and valence levels in beta-PbO2 by hard X-ray photoemission Payne, D. J.; Paolicelli, Guido; Offi, Francesco; Panaccione, G.; Lacovig, P.; Beamson, G.; Fondacaro, A.; Monaco, G.; Vanko, G.; Egdell, R. G. 2009-01 Journal of electron spectroscopy and related phenomena 169 26-34 The core and valence levels of beta-PbO2 have been studied using hard X-ray photoemission spectroscopy (hv = 6000 eV and 7700 eV). The Pb 4f core levels display an asymmetric lineshape which may be fitted with components associated with screened and unscreened final states. It is found that intrinsic final state screening is suppressed in the near-surface region. A shift in the O 1s binding energy due to recoil effects is observed under excitation at 7700 eV. It is shown that conduction band states have substantial 6s character and are selectively enhanced in hard X-ray photoemission spectra. However, the maximum amplitude in the Pb 6s partial density of states is found at the bottom of the valence band and the associated photoemission peak shows the most pronounced enhancement in intensity at high photon energy.