Quantum well states of sp- and d-character in thin Au and Ag films on W(110) and their analysis in the framework of the simplest atomic-limit-approximation

Series of photoemission spectra with pronounced quantum well states (QWS) of sp- and d-character are presented for ultra-thin overlayers of Au and Ag beginning from submonolayer coverages and up to thicknesses of 10-12 monolayers. The spectra for both systems are characterized by step-like changes in binding energies of corresponding QWS's at the initial stages of Au and Ag deposition related to formation of individual monolayers. For thicknesses of more that 5-7 monolayers, no step-like changes can be distinguished and rather continuous QWS energies are observed. The spectra are analyzed from the viewpoint of atomic limit electronic structure in the framework of the simplest linear atomic chain approximation with the chain length corresponding to the thickness of the adsorbed overlayer and oriented perpendicular to the surface. The agreement obtained between experimental results and theoretical estimates shows that the problem of QWS's in ultra-thin layers can be solved from the viewpoint of transition from atomic-like to solid-like electronic structure.