Angle-resolved x-ray-photoemission study of the surface disordering of Pb(100)

The temperature-dependent forward scattering of the 4${\mathit{f}}_{7/2}$ core-level electrons is studied for the [001] and [011] azimuths of Pb(100) using x-ray photoelectron diffraction. Below about 550 K, the decrease in the forward-scattered intensity is attributed to the Debye-Waller effect. Above this temperature, additional attenuation is observed and is attributed to surface disorder. The rate of attenuation dramatically increases above approximately 585 K, and evidence for logarithmic divergence of the thickness of the disordered layer is seen, along with a slight anisotropy that favors disordering along the [011] azimuth. Through analysis of the [001] azimuth, we estimate the disordered layer thickness to be about 4–5 monolayers at 599 K.