Schumann, F. O., Winkler, C., Kirschner, J.

Mapping out electron-electron interactions in angular space

New Journal of Physics

**9**, pp 372/1-14 (2007)

Many-body effects in solids are related to the correlation among electrons. This mutual interaction between the electrons can be probed by electron pair emission spectroscopy. We have investigated the electron pair emission from a LiF(100) surface upon excitation with low kinetic energy electrons. Our angular distributions clearly show that the emission direction of one electron is surrounded by a reduced intensity of the other electron. This depletion zone of electronic intensity is a manifestation of the exchange and correlation hole. We show that we are able to observe the full extension and shape of the depletion zone. It has an angular extension of ≈ 1.2 rad and is independent of the electron energy. Additionally, we discovered that the angle between the trajectories of the electrons has a profound effect on the two-dimensional energy distribution.