The wetting of thin Ag films on Cu (111) is characterized in detail with angle-resolved photoelectron spectroscopy. After constructing disordered Ag films on Cu (111), we monitored the evolution of their layer-resolved Shockley states during wetting. Our results provide the first observation of a transitional state, which implies a coexistence of clean Cu (111), 1 ML of Ag on Cu (111), and 2 ML of Ag on Cu (111). The evolution of these Shockley states indicates a two-process model of wetting.
