Adsorbate-induced shifts of electronic surface states: Cs on the (100) faces of tungsten, molybdenum, and tantalum
The adsorption of cesium on the (100) faces of W, Mo, and Ta for coverages between 0 and 1 monolayer is studied by angle-resolved ultraviolet photoemission spectroscopy with use of synchro- tron radiation, by electron-energy-loss spectroscopy, and by low-energy electron diffraction. With increasing cesiation, the W(100) surface state at Gamma-bar located 0.3 eV below the Fermi level is shifted by up to 1.0 eV to larger binding energies while remaining sharp and intense. A similar behavior is observed on Ta(100), whereas on Mo(100) the shift of 0.9 eV of this surface state is accompanied by a pronounced attenuation of its intensity. These experimental shifts are shown to be in excellent agreement with all-electron local-density-functional results obtained with the full-potential linearized augmented-plane-wave method for Cs monolayers on the W(100) and Mo(100) surfaces. Based on these ab initio results, the electronic origin of the shifts is understood by the formation of strongly polarized covalent bonds between the d-like surface states and the Cs 6s--derived valence states. It is argued that even at high Cs coverages, the main electron-energy-loss peaks, which are observed between 1 and 2 eV, could be interpreted as Cs 6s..-->..6p--like interband transitions rather than as surface-plasmon peaks.
- Research Organization:
- Service de Physique des Atomes et des Surfaces, Centre d'Etudes Nucleaires de Saclay, F-91191 Gif-sur-Yvette Cedex, France and Laboratoire d'Utilisation du Rayonnement Electromagnetique (LURE), Universite de ParisSud, F-91405 Orsay Cedex, France
- OSTI ID:
- 5625581
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Vol. 31:8
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CESIUM
ADSORPTION
MOLYBDENUM
ENERGY LEVELS
SORPTIVE PROPERTIES
TANTALUM
TUNGSTEN
BINDING ENERGY
CRYSTAL FACES
LAYERS
PHOTOEMISSION
SURFACE PROPERTIES
SYNCHROTRON RADIATION
WORK FUNCTIONS
ALKALI METALS
BREMSSTRAHLUNG
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION
ENERGY
FUNCTIONS
METALS
RADIATIONS
SECONDARY EMISSION
SORPTION
TRANSITION ELEMENTS
360104* - Metals & Alloys- Physical Properties