Effect of an Atomically Thin Dielectric Film on the Surface Electron Dynamics: Image-Potential States in the [Formula presented] System

The effect of an atomically thin Ar layer on the image-potential states on Cu(100) surfaces is studied in a joint experimental-theoretical study, allowing a detailed analysis of the interaction between a surface electron and a thin insulator layer. A microscopic theoretical description of the Ar layer is developed based on mutually polarizing Ar atoms. Account of the 3D Ar layer structure allows one to predict energies and lifetimes of the image states in excellent agreement with the observations. The Ar layer, even as thin as one monolayer, is efficiently insulating the state from the metal.