Hybridization of electronic bands along the〈110〉axis in platinum observed by spin-polarized, momentum-resolved photoemission

Spin-polarized, angle-resolved, ultraviolet photoemission spectra of the normal emission from a clean, (1×{}2) reconstructed platinum (110) surface have been measured at the Berlin synchrotron storage ring BESSY using circularly polarized, normally incident light. Along low-symmetry directions, such as {Σ}, no general theoretical prediction about the sign or magnitude of the spin polarization can be made. The present experimental results show spin-polarization peaks with maximum values of 20--30? The peaks in the intensity and spin-polarization spectra may be understood by considering the different dipole-selection rules for these quantities. The spin-polarization data make it possible to trace qualitatively the hybridization of the initial-state bands along the {Σ} direction. One dispersionless peak with virtually no spin polarization cannot be explained by direct bulk transitions. Since this peak is very sensitive to surface reconstruction and to CO adsorption, it is tentatively attributed to emission from a region of high surface density of states.