Probing wave functions at step superlattices: confined versus propagating electrons

Electron wave functions at lateral nanostructures can be readily explored using photoemission with tunable synchrotron radiation. Such systems are ideal for applications in nanotechnology because they are easily accessed by read–write devices that scan across a surface. As model system here we use vicinal Au(111) surfaces, with an array of terraces separated by straight, monatomic steps, which exhibit atomically accurate periodicity due to an intrinsic surface reconstruction. We analyze two extreme cases where electrons are either localized into lateral quantum-well states or propagating across the step superlattice. We are able to probe the electron probability density at the lateral quantum-wells as well as the Fourier spectrum of the two-dimensional (2D) superlattice states.