REFLECTIVITY AND SCATTERING MEASUREMENTS OF AN ADVANCED X-RAY ASTROPHYSICS FACILITY TEST COATING SAMPLE

Reflectivity and scattering profile measurements were made on a gold-c oated witness sample produced to evaluate mirror coatings for the Adva nced X-ray Astrophysics Facility program. Reflectivity measurements we re made at Al K, Ti K, and Cu K energies as a function of incident gra ze angle, The results are fit to a model that includes the effects of roughness, particulate and organic contamination layers, and gold-coat ing density. Reflectivities are close to theoretical, with the differe nce being well accounted for by 4.1 Angstrom of roughness at spatial f requencies above 4 mu m(-1), a gold-coating density equal to 0.98 bulk , and a surface contaminant layer 27 Angstrom thick. Scattering measur ements extending to +/- 35 arcmin of the line center were obtained by the use of Al K x rays and incidence angles from 0.75 degrees to 3 deg rees. The scattering profiles imply a power spectral density of surfac e-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 mu m(-1) and 4 mu m(-1) of 3.3 Angstrom. Combining the roughness es derived from both the reflectivity and scattering measurements yiel ds a total roughness of 5.3 Angstrom for scattering frequencies betwee n 0.05 mu m(-1) and 15,000 mu m(-1).