Regensburg 2010 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.82: Poster

Dienstag, 23. März 2010, 18:30–21:00, Poster B1

Electron coincidence spectroscopy of the neutralization of slow Helium ions above metal surfaces — •Christian Tusche and Jürgen Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany

The neutralization of highly charged ions, scattered at a single-crystal metal surface with kinetic energies of a few 10 eV, is usually accompanied by a number of electrons ejected from the target or from the projectile. For instance, neutralization of ground state He⁺ ions proceeds by Auger neutralization, emitting an Auger electron from the metal. In contrast, He²⁺ neutralization can proceed along several paths. E. g. a double electron capture into the outer He-2s and -2p shells is followed by the emission of a He-KLL Auger electron.

The experimental observation that almost all of the scattered ions leave the surface in the neutral ground state requires that a couple of electron-capture and -emission processes take place on each scattering event. Using electron coincidence spectroscopy, we detect electrons emitted form two such steps in the neutralization cascade of 30 eV He²⁺ ions. The experiment employs two separate electron analyzers. The first one triggers the detection, while the second analyzer records all electrons that arrive within a time window of a few ns. Our results suggest that each ion neutralized at the surface emits two electrons – one in the high energy part of the spectrum (20 eV - 40 eV) and one in the low energy part – with a high probability.