X-Rays and X-Ray Diffraction

TLDR: The wavelength range of X-rays is approximately 0.1-100A, but for the purposes of practical X-ray crystallography, the range used is restricted to 0.7-2.5A as discussed by the authors.

Abstract: X-rays are an electromagnetic radiation of short wavelength, and can be produced by the sudden deceleration of rapidly moving electrons at a target material. If an electron falls through a potential difference of V volt, it acquires an energy eV electron-volt (eV), where e is the charge on an electron. This energy may be expressed as quanta of X-rays of wavelength λ, where each quantum is given by $$ \lambda = hc/(eV) $$ h being the Planck constant and c the speed of light in vacuum. Substitution of numerical values into (3.1) leads to $$ \lambda = 12.4/V $$ where V is measured in kilovolt and λ is given in Angstrom units (A). The wavelength range of X-rays is approximately 0.1–100A, but for the purposes of practical X-ray crystallography, the range used is restricted to 0.7–2.5A.