Berlin 2005 – wissenschaftliches Programm
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A: Atomphysik
A 13: Poster HU 2
A 13.13: Poster
Dienstag, 8. März 2005, 08:30–18:30, Poster HU
Two-electron photoemission from polarized atoms — •Nikolay Kabachnik1,2 and Jamal Berakdar3 — 1Fakultaet fuer Physik, Universitaet Bielefeld, 33615 Bielefeld, Germany — 2Institute of Nuclear Physics, Moscow State University, Moscow 119992, Russia — 3Max-Planck Institut fuer Mikrostrukturphysik, 06120 Halle, Germany
Double ionization of a polarized atom by a single photon with an arbitrary polarization is theoretically considered. General expressions for the triple differential cross section are obtained and analyzed. We point out the existence of a circular and a linear dichroism in the angular distributions of photoelectrons. Generally two types of sources for the dichroism are distinguished: one connected with the initial polarization of the target, and the another one is related to the two-electron final-state properties. We show how these two types of dichroic effects can be experimentally investigated separately by choosing appropriately the detection geometry. As an example, the photo-double ionization of 2P excited and polarized states of atomic helium is considered. We show that a study of the circular dichroism in double photoionization allows to map out the phase properties of the two-electron wave function. Possible applications of circular dichroism measurements to the study of superconductors and orbitally ordered materials are discussed. In particular, we demonstrate that under certain experimental arrangements the circular dichroism in double photoemission can be employed as a sensor for the existence of two-particle orbital orientation in correlated systems and as an indicator for the spontaneous breaking of time-reversal symmetry.