Two-dimensional angular correlation of annihilation radiation study of positron interactions with surfaces of aluminum

Journal Article · Wed Mar 01 00:00:00 EST 1989 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.39.3966· OSTI ID:6452641

Chen, D M; Berko, S; Canter, K F; Lynn, K G; Mills, Jr, A P; Roellig, L O; Sferlazzo, P; Weinert, M; West, R N

Studies were made of the interactions of positrons with three low index surfaces of aluminum ((100), (110), and (111)) at room temperature with the aluminum surface at elevated temperatures and with oxygen adsorption on the aluminum surface. Our measurements using the improved two-dimensional angular correlation of annihilation radiation technique on surfaces support three established processes: spontaneous positronium (Ps) formation and emission, positrons bound in a surface state, and surface-state positrons thermally desorbed as Ps atoms. A method has been developed to accurately separate these components. The positron surface-state annihilation spectra are nearly isotropic for all three Al surfaces, which indicates a lateral localization and is inconsistent with either the ideal image-potential-induced bound state or the physisorbed Ps state. The thermal Ps momentum distributions agree well with the thermostatistical emission mechanism. The momentum distributions of the directly emitted Ps atoms are found to be very sensitive to the surface conditions, and to reflect the electron density of states near the surfaces, thus suggesting a new surface spectroscopy, angle-resolved Ps spectroscopy.

• Research Organization: City College of the City University of New York, Convent Avenue, New York, New York 10031
• OSTI ID: 6452641
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 39:7
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM
POSITRON COLLISIONS
SORPTIVE PROPERTIES
OXYGEN
CHEMISORPTION
ANGULAR CORRELATION
ANNIHILATION
DESORPTION
ELECTRONIC STRUCTURE
EMISSION SPECTROSCOPY
POSITRONIUM
POSITRONIUM CHEMISTRY
SURFACE PROPERTIES
VAN DER WAALS FORCES
BASIC INTERACTIONS
CHEMICAL REACTIONS
COLLISIONS
CORRELATIONS
ELECTROMAGNETIC INTERACTIONS
ELEMENTS
INTERACTIONS
METALS
NONMETALS
SEPARATION PROCESSES
SORPTION
SPECTROSCOPY
656003* - Condensed Matter Physics- Interactions between Beams & Condensed Matter- (1987-)