Correlated positron-electron emission from LiF (100)

Using two hemispherical energy analyzers with transfer lenses we have observed positron-electron pair emission from a surface upon low energy positron impact. An 85 eV positron beam from the NEPOMUC positron source was incident upon a LiF(100) surface and emitted electrons were detected in coincidence with the positrons. Energy analysis of the positron-electron pair confirms that electrons are emitted from the valence band upon positron impact. Electron-electron pairs emitted upon electron and positron impact are also discussed. The information obtainable from these experiments has the potential to provide important insights into electron-electron correlation in solids.