ANGLE-RESOLVED PHOTOEMISSION-STUDY OF HALF-MONOLAYER O AND S STRUCTURES ON THE RH(100) SURFACE

The valence-band photoemission of the Rh(100)-c(2X2)-O, Rh(100)-(2x2)p 4g-O, and Rh(100)c(2x2)-S surfaces has been investigated using an inci dent photon energy of 38 eV, along both the Gamma X' and Gamma M' dire ctions. Local density of slates calculations have also been performed for the c(2X2)-O and c(2x2)-S phases using density-functional theory, For each surface overlayer the angle-resolved photoemission measuremen ts show significant differences in the dispersion of features with bin ding energies between 3 and 6 eV. These peaks are assigned with refere nce to the density of states calculations, and the origins of. the dif ferences in dispersion are discussed in relation to the different geom etric structures.