Photoemission and electron-stimulated desorption studies of H on W(110): Single- versus two-binding-site models
The chemisorption of H on W(110) at room temperature is studied with the use of angle-integrated photoemission and electron-stimulated desorption (ESD). The ESD cross sections of H/sup +/ are found to be sol low that no significant H/sup +/ signals with meaningful ion energy distributions are observed. The photoemission results show, however, two types of H adatoms, referred to as ..beta../sub 2/ and ..beta../sub 1/ states, for this chemisorptive system. Both states are found to appear simultaneously rather than sequentially as suggested by previous studies, and exhibit a simple 1-theta adsorption kinetics with different initial sticking coefficients. The ..beta../sub 2/ state induces two binding energy levels at -2.0 and -6.0 eV, respectively, whereas the ..beta../sub 1/ state induces a level at -3.8 eV. The work-function change (with a maximum value of -0.45 eV) is found to follow exactly with the intensity of the ..beta../sub 2/ state. These results are found to be compatible with the two-binding-site model, inherently suggested by the reflection high-enery electron-diffraction data. However, the results can also be consistent with a single-binding-site model suggested by a recent angle-resolved photoemission and inelastic electron scattering study. A model based on the present results is proposed and critically compared with previous studies. Unresolved problems associated with both single- and two-binding-site models are also discussed.
- Research Organization:
- Physcis Department, Brookhaven National Laboratory, Upton, New York 11973
- OSTI ID:
- 5149914
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 25:10; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360104* -- Metals & Alloys-- Physical Properties
CHEMICAL REACTIONS
CHEMISORPTION
COHERENT SCATTERING
DIFFRACTION
ELECTRON DIFFRACTION
ELEMENTS
EMISSION
FUNCTIONS
HYDROGEN
MEDIUM TEMPERATURE
METALS
NONMETALS
PHOTOEMISSION
SCATTERING
SECONDARY EMISSION
SEPARATION PROCESSES
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
TRANSITION ELEMENTS
TUNGSTEN
WORK FUNCTIONS