Circular Dichroism and Spin Polarization in Photoemission from Adsorbates and Non-Magnetic Solids

Spin-resolving techniques in photoemission are presently attracting wide interest because they can provide a detailed insight into specific aspects of electronic structure and the dynamics of the photoexcitation process. Recent experimental work in the field of non-magnetic systems is reviewed with emphasis on the complementary nature of the information gained by exploiting the photon- and/or electron-spin. A very promising achievement is the verification of circular dichroism (CDAD) in the angular distribution of photoelectrons. It arises without spin-orbit interaction through an interference of final-state partial waves. Every aligned or oriented target (molecular adsorbates, single crystals) should in principle show this effect in photoemission with circularly polarized light. Electron-spin polarization (ESP) in photoemission is induced by circularly polarized light as a direct consequence of spin-orbit interaction. This type of spectroscopy thus provides a unique method for determining the symmetries of electronic bands of high- Z materials. Recent examples of both categories are discussed.