Experimental and theoretical study of the electronic structure of HgO and Tl2O3

Per Anders Glans, Timothy Learmonth, Kevin E. Smith, Jinghua Guo, Aron Walsh, Graeme W. Watson, Fabio Terzi, Russell G. Egdell

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Abstract

The electronic structures of HgO and Tl2O3 have been investigated by valence and core-level x-ray photoemission, x-ray absorption, and x-ray emission spectroscopies. Valence-band photoemission under Al Kα excitation is dominated by the metal 5d partial density of states and thus provides a sensitive probe of shallow core mixing into the O 2p valence-band states. Conversely O K shell emission is determined by the O 2p partial density of states and therefore allows the extent of corresponding mixing of O 2p character into the shallow core states to be measured. The experimental work is supported by band-structure calculations carried out within the framework of density-functional theory. It is shown that the bonding in HgO involves significant mixing between O 2p states and both Hg 6s and shallow core 5d states: the calculated O 2p partial density of states mirrors the O K shell emission spectrum and reveals significant O 2p character within the shallow core Hg 5d states. There is, however, little direct on-site mixing between the Hg 6s and 5d states. In Tl2O3, the hybridization of the deeper metal 5d states with O 2p states is much less pronounced than in HgO. Moreover, the states at the bottom of what is conventionally regarded as the O 2p valence band are found in fact to have very strong Tl 6s atomic character. The photoemission spectrum of Tl2O3 shows a well-defined metallic Fermi edge: the shape of the structure around the photoemission onset suggests that the metallic nature of Tl2O3 arises from an occupation of states above the main valence-band edge, probably arising from oxygen vacancy defects. The conduction electrons of Tl2O3 are strongly perturbed by ionization of Tl core levels, giving rise to distinctive plasmon satellites in core x-ray photoemission spectroscopy.

Original languageEnglish
Article number235109
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume71
Issue number23
DOIs
Publication statusPublished - 2005 Jun 15

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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