Circular dichroism in photoemission from non-magnetic materials

Circular dichroism in the angular distribution (CDAD) of photoelectrons is a unique feature appearing if the emission is excited by circularly polaris ed Synchrotron Radiation. It was first predicted to appear in emission from oriented molec;Ies. Therefore, first experiments on adsorbed molecules hav e been done in restricted geometries. Later it was found in experiments tha t the solid surface itself implies the break of symmetry that is needed to observe CDAD in emission from non-magnetic materials. The CDAD in emission from adsorbates or surfaces is a direct consequence of photoelectron diffra ction. The distribution of the CDAD in the hemisphere above the sample can be interpreted as hologram. It will be shown how this type of dichroic holo gram can be used to reconstruct the real space distribution of the atoms in a solid, or in an adsorbate - substrate system. Different elements can be identified in compounds or alloys due to the elemental sensitivity of X-ray photoemission. As further application it will be shown how CDAD can be use d in photoemission microscopy as a contrast giving mechanism.