Cu K-alpha

Copper K-α is an x-ray energy frequently used on labscale x-ray instruments. The energy is 8.04 keV, which corresponds to an x-ray wavelength of 1.5406 Å.

This causes the prefactor in the scattering equation to be:

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle k = \frac{2 \pi}{\lambda} = 4.0784 \, \mathrm{\AA}^{-1} }