X-Ray Reflectivity Study of the Surface of Liquid Gallium

Abstract

X-ray reflectivity from the surface of liquid gallium was measured under ultrahigh vacuum conditions using a novel technique for curved surfaces. The small deviations between the measured and theoretical Fresnel reflectivity for an ideally sharp flat interface for wave-vector transfer (\lesssim)0.5 Å(^{-1}) imply an interfacial width for the electron density profile of (\lesssim)1.3(\pm)0.2 Å. This is consistent with a model of atomic close packing which lacks structure along the surface normal at length scales >10 Å.