Measurement of Soft X-Ray Absorption by Al, Cr, and Ni Using Synchrotron Radiation

The X-ray absorption of thin films of Al, Cr, and Ni was measured using synchrotron radiation to determine their mass absorption coefficients. The wavelength region was 1.25-6 nm. Sample films were prepared on a polycarbonate membrane by evaporation deposition in the same chamber used for the X-ray absorption measurements in order to avoid sample oxidation and/or the introduction of impurities from air. Plots of the mass absorption coefficients calculated from the X-ray absorption data against wavelength showed that anomalous deviations occurred in several wavelength regions where the curves should be monotonic. Such deviations can be attributed to the second-order light included in the incident light.