Soft x-ray reflectivity and structure evaluation of Ni/Ti-based multilayer x-ray mirrors for water-window region

We fabricated Ni/Ti and Ni-N/Ti-N multilayer mirrors use as a grazing-incident angle reflector to focus x-ray micro-beams. The multilayer structures were fabricated by magnetron sputtering. The layer structures were evaluated by using an x-ray diffractometer and the soft x-ray reflectivities were measured at Beamline 6.3.2 at the Advanced Light Source (ALS). Although the Ni/Ti multilayer has a high interface roughness of about 1.36 nm, the soft-x-ray peak reflectivity of this mirror showed fairly high reflectivity of 39%, at just above the Ti-absorption edge with a 9-degree incident angle. The peak reflectivity of Ni-N/Ti-N multilayer mirrors was 36% in almost the same conditions as the reflectivity measurement of the Ni/Ti multilayer. (author)