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Positron-induced emission of electron-positron pairs from solid surfaces
F Giebels1, H Gollisch, R Feder
1Theoretische Festkörperphysik, Universität Duisburg-Essen, D-47048 Duisburg, Germany.
Summary
Positron-electron pair emission from crystal surfaces is calculated using a new method. This positron surface reaction, (positron, electron-positron), reveals unique angular distributions influenced by Coulomb interactions.
Area of Science:
- Surface Science
- Quantum Mechanics
- Materials Science
Background:
- Positron-solid interactions can lead to the emission of electron-positron pairs.
- Understanding these interactions is crucial for surface characterization and materials analysis.
Purpose of the Study:
- To develop and present a method for calculating the cross section of the (positron, electron-positron) surface reaction.
- To analyze the characteristics of emitted electron-positron pairs from crystalline surfaces.
Main Methods:
- Utilizing a theoretical framework representing the two-particle final state with electron and positron diffraction states coupled by a correlation factor.
- Employing first-principles density functional theory for electron-solid and positron-solid quasi-particle potentials.
- Numerical calculations for Cu(111) surface.
Main Results:
- The energy distributions correlate with the valence electron density of states.
- Positron-induced pair emission exhibits a central accumulation zone in angular distributions due to Coulomb interaction, unlike electron-induced emission.
- Sharp features at larger angles are attributed to single-particle surface resonances.
Conclusions:
- The developed method provides a way to calculate positron-induced electron-positron pair emission cross sections.
- The study highlights distinct differences between (positron, electron-positron) and (electron, 2electron) emission processes.
- Results offer insights into surface electronic structure and interactions.
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