Laterally graded multilayers and their applications

Laterally graded multilayers consisting of uniform W layers and wedge-shape d C layers have been made at the Advanced Photon Source deposition lab for tunable x-ray double-monochromator applications. The double monochromator h as two identical graded multilayers in series, as in the conventional doubl e-crystal monochromator arrangement. By letting the x-ray beam hit slightly different (bilayer) d spacing on each multilayer, one can adjust the bandp ass and peak energy of the transmitted beam. Also, since the Bragg angles o f the two multilayers are not constrained to be the same, the angle of the transmitted beam can be varied in the vertical plane. This option may be an attractive alternative to the conventional way of studying liquid surfaces in reflectivity and grazing-incidence diffraction measurements. The graded multilayer comprised 60 bilayers of W and C on 100 X 25 X 3 min float glas s with a d spacing varying from 35 to 60 Angstrom and an average gradient o f 0.27 Angstrom /mm in the long direction. The films were made by dc magnet ron sputtering with the sputtered atoms passing a contoured mask while the substrate was moving. Two different masks were designed to produce either a uniform (for W) or graded (for C) thickness profile. The multilayer and gr aded multilayers have many other novel applications. Potential applications in x-ray fluorescence detection and x-ray standing wave experiments will b e discussed. (C) 2001 American Vacuum Society.