The specular and nonspecular x-ray reflectivity of a rough multilayer is calculated on the basis of the distorted-wave Born approximation. The theory explains the existence of maxima in the angular distribution of a nonspecularly reflected wave. The interface roughness has been characterized by root-mean-square roughness, lateral correlation length, and the fractal dimension of the interface. It has been demonstrated that these parameters can be obtained from nonspecular reflectivity mreasurements. Calculations based on this theory compare well with data measured on rough layered samples.

• Received 15 September 1992

DOI:https://doi.org/10.1103/PhysRevB.47.15896