Bochum 2015 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

P: Fachverband Plasmaphysik

P 12: Helmholtz Graduate School for Plasma Physics I

P 12.2: Fachvortrag

Dienstag, 3. März 2015, 14:25–14:50, HZO 50

Electronic correlations during the neutralization of strontium ions on gold surfaces — •Mathias Pamperin, Franz Xaver Bronold, and Holger Fehske — Institut für Physik, Universität Greifswald, 17489 Greifswald, Germany

Wall recombination of positively charged ions is one of the main surface-based loss processes for positive ions in a low-temperature gas discharge. It thus affects the overall charge balance of the discharge significantly. Depending on the electronic structure of the ion and the wall electronic mixed-valence correlations may lead to an unexpectedly high recombination probability with an anomalous temperature dependence. There is experimental evidence that this is the case for strontium ions hitting a gold surface. Because of its fundamental importance we analyzed this particular charge-transferring atom-surface collision theoretically using an Anderson-Newns model and non-equilibrium Green function techniques. Our results for the neutralization probability do not yet agree with the experimental data quantitatively. The order of magnitude can be however reproduced as well as the tendency of a negative temperature dependence at high temperatures. The projectile's time-resolved spectral densities show moreover a strong enhancement near the Fermi energy, which is a clear indication that mixed-valence correlations are present. Refinements of the theory necessary to bring experimental and theoretical data in better agreement will be discussed. Supported by the DFG through CRC/Transregio TRR24 and the Federal State of Mecklenburg-Vorpommern through the International Helmholtz Graduate School.