Synchrotron X-Ray Scattering from the Al(110) Surface at the Onset of Surface Melting

We present a grazing-angle x-ray scattering study of the onset of surface melting at the Al(110) surface. By a detailed study of the temperature dependence of the (002) Bragg profile for vanishing perpendicular momentum transfer we obtained new information on the properties of the near-surface crystallinity when the surface undergoes disordering. We conclude that the Al(110) surface starts to "melt" at T0 (770 ± 25) K. For T ≥ T0 a growth of the disordered surface layer is observed. Strong near-surface anharmonic lattice vibrations and surface roughening effects occur as precursors to the onset of surface melting. Our results are compared with recent results from ion shadowing and LEED experiments and molecular dynamics calculations on the same system.