Reflectivity and scattering measurements of an Advanced X-ray Astrophysics Facility test coating sample.

Reflectivity and scattering profile measurements were made on a gold-coated witness sample produced to evaluate mirror coatings for the Advanced X-ray Astrophysics Facility program. Reflectivity measurements were made at Al K, Ti K, and Cu K energies as a function of incident graze angle. The results are fit to a model that includes the effects of roughness, particulate and organic contamination layers, and gold-coating density. Reflectivities are close to theoretical, with the difference being well accounted for by 4.1 Å of roughness at spatial frequencies above 4 µm(-1), a gold-coating density equal to 0.98 bulk, and a surface contaminant layer 27 Å thick. Scattering measurements extending to ±35 arcmin of the line center were obtained by the use of Al K x rays and incidence angles from 0.75° to 3°. The scattering profiles imply a power spectral density of surface-scattering frequencies that follows a power law with an index of -1.0 and a total surface roughness for the spatial frequency band between 0.05 µm(-1) and 4 µm(-1) of 3.3 Å Combining the roughnesses derived from both the reflectivity and scattering measurements yields a total roughness of 5.3 Å for scattering frequencies between 0.05 µm(-1) and 15,000 µm(-1).