Lateral confinement of surface states on stepped Cu(111)

By means of scanning tunneling microscopy we observe the lateral confinement of the two-dimensional electron gas of a s,p-like surface state by a regular distribution of steps on vicinal Cu(111). The surface state appears with a reduced binding energy as a result of scattering at steps and partial confinement within the terraces, as revealed by local scanning tunneling spectroscopy. The energy shift of the bottom of the surface state band is measured for several vicinal Cu surfaces with angle-resolved photoemission and found to be consistent with a simple one-dimensional Kronig-Penney model.