Optical constants for coated thin films in the soft x-ray region

We present optical constants for Ti, V, and Ni in the 2–4.5 nm wavelength region. The reflected synchrotron radiation intensity was measured at more than 30 incident angles for each wavelength. A protective layer of carbon was sputtered onto each sample to prevent surface oxidization. A three-phase model was used to analyze the data. Instead of replacing some of the parameters by values determined by other experimental methods, eight parameters were simultaneously used in the least squares fitting. A 5-nm layer of carbon was found to be thin enough not to cause significant errors in the derived optical constants of the test materials.