Influence of photoelectron diffraction effects on the dichroism and spin polarization of non-magnetic surfaces

The circular dichroism in the angular distribution of photoelectrons from non-magnetic single crystal surfaces such as Si(001) is caused by photoelectron diffraction effects. A simple formula can be derived within the single scattering formalism which describes the observed rotational shift of forward scattering peaks in the photoelectron diffraction pattern with circularly polarized light. The influence of photoelectron diffraction on the spin polarization is discussed for Cu 3p photoelectrons in Cu(001). Calculations of the dependence on both the emission direction and the kinetic energy of the photoelectrons have been carried out using a full spherical wave expansion. It is shown that the photoelectron diffraction causes significant modulations in the intensity of the Cu 3p photoelectrons and therefore in the spin polarization because of a different scattering of the partial waves which superimpose coherently. The theoretical results are compared with available experimental data. (C) 1997 Elsevier Science B.V.