Schumann, F. O., Fominykh, N., Winkler, C., Kirschner, J., Berakdar, J.
Electron pair emission from a Cu(111) surface upon photon absorption
Physical Review B 77, (23),pp 235434/1-8 (2008)
We studied the electron pair emission from a Cu(111) surface upon photon absorption. We found that the energy sharing depends on the angle between the trajectories of the two emitted electrons. The angular distribution of the coincidence intensity displays a zone of reduced intensity, if the emission direction of one electron is fixed. We are able to observe the full extension and shape of this depletion zone. It has an angular extension of ≈ 1.2 rad, which is independent of the electron energy. This depletion zone is a manifestation of the exchange-correlation hole. The experimental results are discussed in connection with a detailed theoretical description.