Novel x-ray diffractometer for liquid surface studies

Abstract

An x‐ray diffractometer for studying the structure of the liquid–vapor interface is described. It is designed to permit reflectivity and scattering studies from liquid surfaces for angles varying from grazing incidence, below the critical angle for total external reflection up to angles ∼3° using a rotating anode x‐ray generator. In principle the diffractometer system can be used to study both the density profile normal to the surface and in‐plane structural features. The former is determined by deviations of the measured reflectivity from the Fresnel law of classical optics and the latter from nonspecular scattering. Results obtained using this spectrometer to measure the density profile normal to the surface of water and a liquid crystal are presented.