One-dimensional versus two-dimensional surface states on stepped Au (111)

Surface states at vicinal Au(788) and Au(322) have been investigated with angle-resolved photoemission and synchrotron radiation. Both surfaces are characterized by highly regular one-dimensional step arrays with relatively wide (∼3.9 Å) or narrow (∼1.3 Å) terraces in Au(788) and Au(322), respectively. Depending on the terrace size we observe that surface electrons behave in a completely different way. In Au(788) terraces become one-dimensional, lateral quantum wells that confine surface electrons between adjacent steps. In Au(322) surface electrons propagate across the step array forming two-dimensional superlattice bands. By tuning photon energy and angle we probe fundamental properties of the electron wave functions in both cases.A.Mu. and J.E.O. are supported by the Universidad del Pais Vasco (1/UPV/EHU/00057.240-EA-8078/2000). V.R. and S.R. are supported by the CNRS-ULTIMATECH program, the CRIF and the Universite de Paris 7. V. P.-D. is supported by the Comunidad Autonoma de Madrid (Project No. 07N/0042/98) and the DGICYT (Spain Grant No. PB97-1199).Peer reviewe