Off-gap interface reflectivity of electron waves in Fabry-Perot resonators

The interface reflectivity in the Mg/W(110) metallic quantum well is determined from line-shape analysis of high-resolution photoemission spectra. Moreover, a quick reflectivity drop is found away from projected band gaps of the appropriate symmetry near E-F, such that the interface reflectivity overcomes the bulklike quasiparticle lifetime as the dominant line broadening mechanism at the Fermi energy. A nearly-free-electron model calculation for the W(110) substrate band structure demonstrates that coherent wave-function scattering is the relevant mechanism that determines the interface reflectivity in the resonator.