Berlin 2001 – wissenschaftliches Programm

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A: Atomphysik

A 13: Photoionisation I (joint session A and MO)

A 13.7: Vortrag

Donnerstag, 5. April 2001, 17:15–17:30, H1012

Dichroism in Atomic Photoionzation — •Georg Prümper — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany

The dependence of the photoelectron intensity on the direction of the polarization axis of the ionizing radiation with respect to the direction of magnetization of the target is called dichroism. This effect enables magnetization studies of thin films. In the field of atomic physics the dichroism is used to obtain detailed information on the photoionization process in particular on the phase shift between two outgoing partial photoelectron waves.

Using circularly as well as linearly polarized synchrotron radiation we have performed dichroism measurements on atomic oxygen, iron and thallium. Significant effects were found in the case of non-resonant photoionization as well as on autoionization resonances. The measurements on oxygen can be well described by calculations using an Hartree-Fock model. The data of the heavier elements iron an thallium however clearly shows the effect of electron correlation as well as the coupling of different continuum channels. In the case of iron also non-resonant circular dichroism is observed over a broad photon energy range which is in contrast to thin film studies of the 3d transition metals where dichroism is found only at the absorption edges.