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(2×{}2)-O, Rh(100)-(2×{}2)p4g-O, and Rh(100)- c(2×{}2)-S surfaces has been investigated using an incident photon energy of 38 eV, along both the {Γ}X{'} and {Γ}M{'} directions. Local density of states calculations have also been performed for the c(2×{}2)-O and c(2×{}2)-S phases using density-functional theory. For each surface overlayer the angle-resolved photoemission measurements show significant differences in the dispersion of features with binding energies between 3 and 6 eV. These peaks are assigned with reference to the density of states calculations, and the origins of the differences in dispersion are discussed in relation to the different geometric structures.