Electronic and chemical properties of Li--Au and Cs--Au films on Ru(001)

Journal Article · Thu Jul 01 00:00:00 EDT 1993 · Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States)

DOI:https://doi.org/10.1116/1.578404· OSTI ID:6051322

Rodriguez, J A; Hrbek, J ^[1]; Kuhn, M; Sham, T K ^[2]

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1. Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)
2. Department of Chemistry, The University of Western Ontario, London N6A 5B7 (Canada)

The core and valence levels of Li--Au and Cs--Au films have been studied using synchrotron radiation. For Li--Au, the results of valence-band photoemission show no band gap in the region close to the Fermi level indicating that this compound has metallic properties. In contrast, the valence spectra of CsAu show the typical band gap expected for a highly ionic compound. The formation of alkali-gold bonds induces shifts in the core levels that are not controlled exclusively by changes in the charge of the metal centers. Alloys saturated with Cs or Li show binding-energy shifts of +1.3 or +0.7 eV, respectively, in the Au(4[ital f]) levels. LiAu and CsAu compounds are very reactive toward oxygen. The presence of oxygen shifts the Au(4[ital f]) levels of the alkali-gold alloys toward lower binding energy. The interaction of O[sub 2] with CsAu at 100 K produces O[sub 2][sup 2[minus]] (the only oxygen species at low O[sub 2] exposures) and O[sub 2][sup [minus]]. Annealing of the O[sub 2]/CsAu film to 300 K leads to the disappearance of O[sub 2][sup [minus]] and the appearance of O[sup 2[minus]]. The adsorption of O[sub 2] on Li--Au alloys at 300 K produces the O[sub 2][sup [minus]] ion together with another oxygen species.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6051322
• Journal Information: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States), Vol. 11:4, Issue 4; ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION
OXYGEN
CESIUM ALLOYS
ELECTRONIC STRUCTURE
GOLD ALLOYS
LITHIUM ALLOYS
ANNEALING
BINDING ENERGY
PHOTOEMISSION
RUTHENIUM
SYNCHROTRON RADIATION
THIN FILMS
VALENCE
ALLOYS
BREMSSTRAHLUNG
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION
ENERGY
FILMS
HEAT TREATMENTS
METALS
NONMETALS
PLATINUM METALS
RADIATIONS
SECONDARY EMISSION
SORPTION
TRANSITION ELEMENTS
360104* - Metals & Alloys- Physical Properties