The effect of longer-range waviness on X-ray reflectivity measurements.

A model for calculating the X-ray reflectivity (XRR) of surfaces to extract both roughness and waviness features is presented. Expressions of reflectivity intensity are derived as a function of root-mean-square (RMS) roughness σ, RMS waviness σ, and the cut-off frequency between the features ω. Experiments were conducted at the Advanced Light Source at Lawrence Berkeley National Laboratory, beamline 8.