title: Mapping out electron-electron interactions at surfaces.
abstract: Using a high resolution coincidence technique, we measured for the first time the angular and energy correlation of an electron pair emitted from the valence band of a single crystal upon the impact of an electron with a specified momentum. We observe a hole in the measured two-particle correlation function when the two excited electrons have comparable momentum vectors, a fact traced back to exchange and repulsion among the electrons. We find the hole is not isotropic, has a finite extension, and is strongly suppressed when decoherence is operating.
authors.affiliation: Max-Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany.
authors.forename: F O
authors.initials: FO
authors.lastname: Schumann
authors.forename: J
authors.initials: J
authors.lastname: Kirschner
authors.forename: J
authors.initials: J
authors.lastname: Berakdar