# Is it feasible/possible to use refraction for x-ray spectrum analysis?

In x-ray spectroscopy Bragg reflection off of a crystal is used for spectral analysis. In x-ray diffraction the same principle is used for monochromatizing the x-ray beam from an x-ray tube. For visible light, however, an optical prism is used to decompose the spectrum. I understand that Bragg scattering would not be feasible for visible light as the wavelength range of visible light (390-700nm vs. 0.01-10nm for x-ray) is much larger than atomic spacing in most crystals (a few angstroms), and the Bragg angle has to be very shallow(?).

Is it feasible to use a prism instead of Bragg reflection in x-ray spectral analysis (i.e., is there a material with low x-ray attenuation and suitable refraction index)? Is there any table of refraction indices for different materials at various wavelengths (alternatively, a table of relative permittivity and relative permeability)?

• As a numerical example, aluminum has an index of refraction of 1.000008 for x-rays with a wavelength $1.6\times 10^{-10}$ m. – user4552 Nov 26 '17 at 23:16
• @BenCrowell Generally in the x-ray region, $n$ is slightly less than unity. (Except near absorption edges.) For example, holes in aluminum can be used as positive lenses spie.org/newsroom/… – Pieter Nov 26 '17 at 23:29