Berlin 2014 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 17: Poster Session - Helmholtz Graduate School for Plasma Physics

P 17.17: Poster

Mittwoch, 19. März 2014, 16:30–18:30, SPA Foyer

Possibility of a Kondo resonance at the wall recombination of positive ions — •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. Together with volume-based charge production and destruction processes it controls the overall charge balance of the discharge. Depending on the electronic structure of the ion and the wall an ion may recombine either via Auger neutralization or via resonant charge transfer. Both processes are of fundamental interest. The time-dependent ion-surface system represents a quantum-impurity system supporting–under appropriate conditions–a Kondo resonance which is one of the paradigms in the physics of highly correlated electrons and should also affect the wall recombination. Indeed He and Yarmoff [1] interpreted the anomalous temperature dependence of the neutralization of Sr⁺ ions at a Au surface in terms of a Kondo resonance. To support this claim we calculated within an Anderson-Newns model the temperature dependence of this particular atom-surface collision using quantum-kinetic equations and a pseudo-particle representation for the electronic configurations of the ion. We found that a Kondo resonance indeed shows up and affects the neutralization rate. To gain further insight we also studied the neutralization of Mg⁺ or Ga⁺ ions at a Au surface where the Kondo effect is not expected.

[1] X. He and J. A. Yarmoff, Phys. Rev. Lett. 105, 176806 (2010).