Orthopositronium study of positron-irradiation-induced surface defects in alumina powder

Journal Article · Wed Jan 01 00:00:00 EST 1992 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.45.9· OSTI ID:5080587

Dauwe, C ^[1]; Mbungu-Tsumbu, ^[2]

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1. Laboratorium voor Magnetisme, Rijksuniversiteit Gent, Proeftuinstraat 86, 9000 Gent (Belgium)
2. Departement de Physique, Universite de Kinshasa, Boite Postale 190 KIN XI (Zaire)

Three-quantum-yield measurements and orthopositronium ({ital o}-Ps)-lifetime spectrometry at low temperatures are used to study the interaction of positronium with the surface in fine powders of aluminum oxide. It is found that electron and/or positron irradiation of the specimen induces surface defects which influence the positronium in three ways: (1) A surface positroniumlike bound state is created, (2) the fraction of {ital o}-Ps escaping from the particles is slightly inhibited, and (3) the escaped {ital o}-Ps is quenched into two-quantum decay upon collisions with the surface defects. It is found that the surface Ps state is not populated at the expense of the interparticle Ps. The most likely surface defects are Al{sup 2+} or Al{sup 0} due to the migration of irradiation-induced interstitials. The techniques of long-lifetime spectrometry and of three-quantum-annihilation-rate measurement could be used to study both the diffusion of bulk defects to the surfaces, and the interactions of {ital o}-Ps to surface defects.

• OSTI ID: 5080587
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 45:1; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM OXIDES
PHYSICAL RADIATION EFFECTS
POSITRONIUM
BOUND STATE
ELECTRON-ATOM COLLISIONS
INTERSTITIALS
LIFETIME
POWDERS
ALUMINIUM COMPOUNDS
ATOM COLLISIONS
CHALCOGENIDES
COLLISIONS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELECTRON COLLISIONS
OXIDES
OXYGEN COMPOUNDS
POINT DEFECTS
RADIATION EFFECTS
664500* - Special Atoms & Molecules- (1992-)
665300 - Interactions Between Beams & Condensed Matter- (1992-)