Quasi-one-dimensional quantized states in an epitaxial Ag film on a one-dimensional surface superstructure.

The in-plane energy dispersion of quantized states in an ultrathin Ag film formed on the one-dimensional (1D) surface superstructure $\mathrm{Si}(111)\mathrm{\text{\ensuremath{-}}}(4\ifmmode\times\else\texttimes\fi{}1)\mathrm{\text{\ensuremath{-}}}\mathrm{In}$ shows clear 1D anisotropy instead of the isotropic two-dimensional free-electron-like behavior expected for an isolated metal film. The present photoemission results demonstrate that an atomic layer at the film-substrate interface can regulate the dimensionality of electron motion in quantum films.