Problem 5.154

A narrow beam of X-rays impinges on the natural facet of a NaCl single crystal, whose density is \(\rho=2.16 \mathrm{~g} / \mathrm{cm}^{3}\) at a glancing angle \(\alpha=60.0^{\circ} .\) The mirror reflection from this facet produces a maximum of second order. Find the wavelength of radiation.