Slow positron studies on single crystals of Ag(100), Ag(111) and Cu(111). [0 to 5 KeV, 300 to 1200/sup 0/K]
Conference
·
OSTI ID:6286117
Monoenergetic positrons were employed to examine positronium formation as a function of sample temperature (300 to 1200 K) and incident energy (0 to 5 keV) on Ag(100), Ag(111) and Cu(111) surfaces with submonolayer contamination. In these metals at the higher temperatures, positronium formation becomes the dominant process. A one-dimensional diffusion model is fit to the data as a function of incident energy. Th positronium fraction is found to be an activated process and is identified as detrapping from a surface state and an estimate of the depth of this trap is extracted. The diffusion length is found to be temperature independent before the onset of vacancy trapping. At the higher temperatures vacancy trapping is observed by the decrease in the positron diffusion length at the higher incident voltages. A vacancy formation energy is extracted from the data and is generally lower than the accepted bulk values. 18 references.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- DOE Contract Number:
- EY-76-C-02-0016
- OSTI ID:
- 6286117
- Report Number(s):
- BNL-26084; CONF-790437-5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
640301 -- Atomic
Molecular & Chemical Physics-- Beams & their Reactions
640303* -- Atomic
Molecular & Chemical Physics-- Positronium
Muonium
& Muonic & Mesic Atoms & Molecules
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
COLLISIONS
COPPER
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DATA
DATA FORMS
DIFFUSION
DIFFUSION LENGTH
ELECTRIC POTENTIAL
ELEMENTS
ENERGY DEPENDENCE
ENERGY RANGE
EXPERIMENTAL DATA
GRAPHS
HIGH TEMPERATURE
INFORMATION
ISOLATED VALUES
KEV RANGE
KEV RANGE 01-10
KINETICS
MEDIUM TEMPERATURE
METALS
NUMERICAL DATA
ONE-DIMENSIONAL CALCULATIONS
POINT DEFECTS
POSITRON COLLISIONS
POSITRONIUM
SILVER
SURFACES
TRANSITION ELEMENTS
TRAPPING
VACANCIES
VERY HIGH TEMPERATURE
Molecular & Chemical Physics-- Beams & their Reactions
640303* -- Atomic
Molecular & Chemical Physics-- Positronium
Muonium
& Muonic & Mesic Atoms & Molecules
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
COLLISIONS
COPPER
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DATA
DATA FORMS
DIFFUSION
DIFFUSION LENGTH
ELECTRIC POTENTIAL
ELEMENTS
ENERGY DEPENDENCE
ENERGY RANGE
EXPERIMENTAL DATA
GRAPHS
HIGH TEMPERATURE
INFORMATION
ISOLATED VALUES
KEV RANGE
KEV RANGE 01-10
KINETICS
MEDIUM TEMPERATURE
METALS
NUMERICAL DATA
ONE-DIMENSIONAL CALCULATIONS
POINT DEFECTS
POSITRON COLLISIONS
POSITRONIUM
SILVER
SURFACES
TRANSITION ELEMENTS
TRAPPING
VACANCIES
VERY HIGH TEMPERATURE