Evidence for grading at polished surfaces from grazing-incidence X-ray scattering

Grazing-incidence specular and diffuse X-ray scattering has been performed on polished surfaces of the glass ceramic Zerodur (registered trademark of Schott Glaswerke, Mainz). Analysis using a distorted-wave Born approximation showed that satisfactory fits to the data could be obtained only if grading was included at the surface. A new formulation of the scattering model has been derived, incorporating such grading. When this was applied, excellent agreement between experiment and theory was obtained with one set of model parameters fitting at all scattering vectors.