Abstract
We report detailed He atom scat te ring mea su re ments of the pho non li ne width for the Ray leigh mode S1 and the resonant mode S3 of Ag(110) along the whole side of the surface Brillouin zone as a function of the sample temperature. The novel behaviour observed for the resonance linewidth is explained by including the mixed-mode nature into the anharmonic calculations performed within the framework of the Born-von Karman model.