THE STRUCTURE OF NA OVERLAYERS ON CU(111) AT ROOM-TEMPERATURE

Thermal desorption spectroscopy (TDS), low energy electron diffraction (LEED), and work function change measurements have been carried out to study the adsorption of sodium on Cu(111) at room temperature. The first layer develops from a disordered phase at low coverage to an evenly spaced incommensurate structure then to a commensurate hexagonal overlayer structure at the completion of the first layer. The work function change passes through a minimum at intermediate coverage, levels off by the completion of the first monolayer, then decreases slightly with increasing Na coverage in the second layer. The measurements will be discussed in relation to other investigations of this and related systems.