MULTIPLE-SCATTERING STUDY OF SYNCHROTRON-RADIATION PHOTOELECTRON DIFFRACTION FROM SI(001)2X2-IN SURFACE

Synchrotron radiation photoelectron diffraction (PED) from the Si(001) 2x2-In surface was measured for the well resolved In 4d spin-orbit dou blet (4d(3/2) and 4d(5/2)) at photon energy of 100 eV. It is found tha t the two diffraction patterns originating from different core-level s tates are notably different from each other. A multiple scattering clu ster method was applied to analyze both PED's. The optimized structure s from the two patterns take essentially a similar parallel In-dimer m odel, but the radial matrix elements and phase shifts of the photoelec tron continuums are different for time two components. We attribute th is unexpected result to a spin-orbit coupling effect near the Cooper m inima.