Direct Surface Structure Determination with Photoelectron Diffraction

Angle-resolved photoemission extended fine structure from adsorbate core levels yields complete, accurate surface structures without resort to trial-and-error comparisons to theory. Scattering peaks from individual substrate atoms were observed with use of S(1s) photoemission from c(2×2)S/Ni(001) and p(2×2)S/Cu(001), along [011]. Fourfold-hollow site geometries were found for both systems, with interatomic distances of R(S-Ni)=2.24(3) {} and R(S-Cu)=2.28(3) {}.