Parts | Days | Selection | Search | Updates | Downloads | Help
O: Fachverband Oberflächenphysik
O 89: Surface Dynamics II
O 89.3: Talk
Friday, March 15, 2013, 11:00–11:15, H33
Emission of correlated positron-electron pairs from surfaces — •Iuri Stefani Brandt1, Zheng Wei1, Frank Oliver Schumann1, and Jürgen Kirschner1,2 — 1Max-PlanckInstitut für Mikrostrukturphysik, Halle, Germany — 2Martin-LutherUniversität, Halle, Germany
The electron correlation is due to the combined action of the Pauli principle and Coulomb interaction. Electron pair emission is a powerful tool to study the aspects of the electron correlation. One way to disentangle the Pauli principle from the Coulomb interaction is to explore correlated positron-electron pair emission upon primary positron impact. This process of positron-electron pair emission is detectable and motivated a theoretical study [1,2]. We developed a dedicated laboratory positron source employing a Na22 isotope which provides a flux of 4x104 e+/s for kinetic energies in the range of 40-70 eV. We employ a symmetric geometry in which the incoming positrons hit the target along the surface normal. The emitted particles are measured in coincidence via a pair of energy dispersive spectrometers. We investigated NiO/Ag(100) and Ag(100) surfaces. In the case of electron pair emission upon primary electron impact we observe a symmetric two-dimensional energy distribution, because electrons are not distinguishable. Contrary to this electrons and positrons are distinguishable leading to an asymmetric two-dimensional energy distribution.
G.A. van Riessen et al., JPCM 20, 442001 (2008).
[2] F. Giebels et al., JPCM 21, 355002 (2009).