Electronic and Lattice Structure of Cesium Films Adsorbed on Tungsten

Data on elastic diffraction and inelastic scattering of electrons by Cs adsorbed on W in monolayer lattices suggest that at monolayer densities equal to about half the bulk density the decay rate of surface plasmons is much greater than for similarly situated monolayers of approximately bulk density. The enhanced decay rate is interpreted as evidence for nonmetallic character of the low-density layer, as proposed by Wigner for a low-density gas and by Mott for low-density aggregates of odd-valence atoms.