Electronic Structure and Dynamics of Quantum-Well States in thin Yb-Metal Films

Quantum-well states above the Fermi energy in thin Yb(111)-metal films deposited on a W(110) single crystal were studied by low-temperature scanning tunneling spectroscopy. These states are laterally highly localized and give rise to sharp peaks in the tunneling spectra. A quantitative analysis of the spectra yields the bulk-band dispersion in Gamma - L direction as well as quasi-particle lifetimes. The quadratic energy dependence of the lifetimes is in quantitative agreement with Fermi-liquid theory.