Effect of the structural anisotropy and lateral strain on the surface phonons of monolayer xenon on Cu(110)

Abstract
The phonon-dispersion curves for a xenon monolayer adsorbed on Cu(110) have been measured using inelastic He scattering. The size and geometry of the substrate unit cell introduces an anisotropic distortion of the xenon monolayer, which is reflected in a strong deformation of the phonon-dispersion curves with respect to the floating two-dimensional (2D) xenon layer. This effect is reproduced in a 2D phonon calculation, based on the Lennard-Jones Xe pair potential. In this way a microscopic relationship between lattice strain, force constants, and surface stress can be established.