The study of some peculiar phenomena in ultra-soft X-ray measurements using synthetic multilayer crystals

Recently there has been rapid progress in both ultra-soft X-ray measurements and thin film analysis by X-ray fluorescence using synthetic multilayer analyzers. However, the use of these multilayer crystals has several potential problems including incomplete spectral 2θ tables and some peculiar background behavior neighboring C Kα and B Kα lines. The spectral 2θ tables of the synthetic multilayer analyzers have been prepared in oder that the interfering spectra for the analyte peaks can be studied. Diffraction by the substrate of the multilayers was observed for the short wavelength X-rays of some heavy elements. Measures have been taken to treat the substrate itself to depress this diffraction. 'Ghost' peaks are produced by the total reflection of ultra-soft X-rays. Fluorescent X-rays are also observed from the excitation of elements in the multilayers. These phenomena become analytical problems because they cause the background to change. A synthetic multilayer having a suitable 2d value is used to reduce the effect of the 'ghost' peaks, i.e., improve the peak separation between the analyte line peak and the 'Ghost' peak. Correction methods for the background behavior have been established to solve these problems. (author)