Ultrathin metallic films may act as quantum boxes when some conditions are met. Here, we discuss these conditions for the simplest case of one-dimensional confinement and we review some of the properties that emerge from the reduced dimensionality of the films. We emphasize the difference between extremely thin layers of up to several monolayers thickness and thicker ultrathin films. Taking the Ag/V(100) system as a case Study, we show the most prominent features of the electronic structure of the films, as revealed by the angular resolved ultraviolet photoemission spectroscopy (ARUPS)
