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TT: Fachverband Tiefe Temperaturen

TT 42: Superconductivity: Fabrication, Properties, Electronic Structure

TT 42.10: Talk

Thursday, March 29, 2012, 17:30–17:45, H 3005

Correlation Effects in the Double Photoemission of Pb(111) — •Robert Wallauer, Stefan Voss, Achim Czasch, Lutz Foucar, Till Jahnke, Horst Schmidt-Böcking, and Reinhard Dörner — Institut für Kernphysik, Universität Frankfurt

The investigation of two electrons emitted by a single photon is particulary sensitive to correlation effects, since their coincident emission is forbidden in the absence of any interaction between them. In order to study this process, we setup an experiment in which we measure two electrons in coincidence and can calculate their complete momentum.

We measured a Pb single crystal in superconducting and normal state at Photon energies between 20 and 40 eV. The emission of Cooperpairs has been predicted for this process. Despite of highly improved pulse analysis tools, it could not be identified so far. For photon energies above 25 eV the DPE current is dominated by Auger-processes involving the 5d(5/2) and 5d(3/2) core levels. Both, Auger- and Photoelectron are detected in coincidence and the interaction between them can be studied energy- and angular-resolved.