Adsorbate induced changes of Debye-Waller factors

The scattering of a molecular beam by a solid surface is sensitive to the vibrational properties of the surface which are changed by the presence of adsorbed molecules. In particular light adsorbates with discrete localized vibrational modes lead to discrete structures in the energy distribution of scattered particles and corresponding structures in the intensities of specular scattering as measured by the Debye-Waller factor. We investigate the dependence of the Debye-Waller factor on various parameters characterizing the adsorbate as well as the scattered particle. It turns out that the intensity of discrete structures in the Debye-Waller factor usually is small. Only in a very restricted range of parameter values one may be able to find observable effects.