X-ray reflectivity from micrometre-scaled surfaces using nanobeams

Sample and diffractometer alignment for grazing-incidence X-ray measurements become ever more crucial once the beam and surface area of interest reach the nanometre scale. Here we show how a point of interest on a surface can be kept in the beam while measuring X-ray reflectivity, even if it is not in the centre of rotation, either because of systematic errors or additional unwanted angle-dependent sample movement. This can be achieved by a 1D trajectory scan varying the angle of incidence (θ), the detector angle (2θ) and the position of the sample along one axis in the scattering plane. As an example, we show the results of X-ray reflectivity measured from a 10 × 10 µm Au island using a 90 nm beam. Data analysis is presented which considers the angle-dependent X-ray beam footprint illuminating both the Au island and the surrounding support.