Helium metastable deexcitation at surfaces

Journal Article · Sat May 01 04:00:00 EDT 1993 · Bulletin of the American Physical Society

OSTI ID:281586

Oro, D M; Soletsky, P A; Zhang, X ^[1]

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1. and others

Spin labeling techniques are being used to investigate the dynamics of metastable atom deexcitation at surfaces. A beam of thermal-energy electron-spin-polarized He(2{sup 3}S) atoms is directed at the surface, and the energy and polarization distributions of the ejected electrons are measured. At clean, high work function metal surfaces He(2{sup 3}S) deexcitation proceeds via resonance ionization of the incident atom followed by Auger neutralization of the resulting He{sup +} ion. The data show that the electrons involved in the neutralization process tend to have antiparallel spins. This spin correlation may be explained in terms of modifications to the local surface electronic structure due to the presence of the He{sup +} ion, and efforts are underway tb model such effects theoretically. Measurements on surfaces comprising several monolayers of Xe frozen on a cooled substrate show features analogous to those observed in gas-phase Penning ionization, suggesting that electron ejection occurs, in part, through Penning ionization of adsorbed atoms. Other features, however, are apparent and can be attributed to interactions with neighboring atoms and to effects introduced by the substrate. These features are being explored further using He(2{sup 1}S) and He(2{sup 3}P) atoms and substrates with different work functions.

• OSTI ID: 281586
• Report Number(s): CONF-9305421--
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 3 Vol. 38; ISSN 0003-0503; ISSN BAPSA6
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ATOM COLLISIONS
DE-EXCITATION
ELECTRON EMISSION
HELIUM
METALS
METASTABLE STATES
WORK FUNCTIONS