Direct Observation of the Surface Segregation of Cu in Pd by Time-Resolved Positron-Annihilation-Induced Auger Electron Spectroscopy
- ZWE FRM II, Lichtenbergstrasse 1, 85747 Garching (Germany)
Density functional theory calculations predict the surface segregation of Cu in the second atomic layer of Pd which has not been unambiguously confirmed by experiment so far. We report measurements on Pd surfaces covered with three and six monolayers of Cu using element selective positron-annihilation-induced Auger electron spectroscopy (PAES) which is sensitive to the topmost atomic layer. Moreover, time-resolved PAES, which was applied for the first time, enables the investigation of the dynamics of surface atoms and hence the observation of the segregation process. The time constant for segregation was experimentally determined to {tau}=1.38(0.21) h, and the final segregated configuration was found to be consistent with calculations. Time-dependent PAES is demonstrated to be a novel element selective technique applicable for the investigation of, e.g., heterogeneous catalysis, corrosion, or surface alloying.
- OSTI ID:
- 21541709
- Journal Information:
- Physical Review Letters, Vol. 105, Issue 20; Other Information: DOI: 10.1103/PhysRevLett.105.207401; (c) 2010 American Institute of Physics; ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ANNIHILATION
AUGER ELECTRON SPECTROSCOPY
COPPER
CORROSION
DENSITY FUNCTIONAL METHOD
HETEROGENEOUS CATALYSIS
LAYERS
PALLADIUM
POSITRONS
SEGREGATION
SURFACES
TIME DEPENDENCE
TIME RESOLUTION
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
CALCULATION METHODS
CATALYSIS
CHEMICAL REACTIONS
ELECTRON SPECTROSCOPY
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
INTERACTIONS
LEPTONS
MATTER
METALS
PARTICLE INTERACTIONS
PLATINUM METALS
RESOLUTION
SPECTROSCOPY
TIMING PROPERTIES
TRANSITION ELEMENTS
VARIATIONAL METHODS