Image states on finite size adsorbate islands: Ar on Cu(1 0 0)

Finite size effects are investigated in the case of image states localised on Ar islands on Cu(1 0 0) surfaces. A wave-packet propagation approach associated to a microscopic description of the Ar layer is used to compute the energies and widths of the quasi-stationary image states confined on the Ar islands. Electron transmission through the island edges is found to induce a very efficient decay process for the confined image states. The possibility of observing these finite size effects, together with an estimate of the minimum island size for which the image states properties converge to those on a full ML is also presented.