Manufacture and performances of rhodium/carbon multilayer x‐ray mirrors

A diode rf‐sputtering technique was used to produce Rh/C multilayers for application in the soft‐x‐ray domain. In situ kinetic ellipsometry is used to calibrate the deposition rates and to analyze precisely the interface structure formation. Grazing x‐ray reflectivity at the Cu‐Kα line (1.54 A), and absolute soft‐x‐ray reflectivity at the Cu‐Lα line (13.33 A) and at the C‐Kα line (44.7 A) are also measured on the same multilayers. A model which assumes a quasi‐sharp C‐Rh interface (4 A thick) and a diffused Rh‐C interface (22 A) in the stack is used to fit the reflectivity curves at the three experimental wavelengths. Reflectivities as high as 22% at 13.3 A and 24% at 44.7 A were measured on a 17‐period multilayer structure having a period of ≂69 A.