X-ray Scatiering Studies of the Melting of Lead Surfaces.

Abstract

Of fundamental importance in understanding melting is the question of premelting (i.e. do surfaces melt at a lower temperature than the bulk). We report the results of an x-ray scattering experiment that has directly measured liquid correlations in Pb(110) and Pb(111) surfaces at temperatures substantially below the bulk melting point of Pb. Surprisingly, significant liquid scattering is observed at ≈230°K or >1/2Tm on both the (110) and the (111) surfaces. On the (110) surface, analysis of the scattered intensity yields 2–3 monolayers of liquid from 575°K to 599°K while substantially less than 1 monolayer of liquid is present on the (111) surface at 599°K.