Thermal expansion of the Ag(111) surface measured by x-ray scattering

We have investigated the structure of the Ag(111) surface, for temperatures between 300 and 1100 K (90% of the bulk melting point), using synchrotron x-ray diffraction. Our data show no evidence of the anomalously large surface thermal expansion previously reported by medium-energy ion-scattering [Phys. Rev. Lett. 72, 3574 (1994)]. At all temperatures we find that the interlayer separations at the surface differ from their bulk counterparts by less than 1%, indicating that the surface expands similarly to the underlying bulk crystal. This behavior is in good agreement with results from molecular dynamics simulations.