Reflection high-energy electron diffraction (RHEED) has become a commonplace technique for probing the atomic surface structures of materials. Under vacuum conditions an electron beam is made to strike the surface of the sample under test at a glancing angle (θ < 10^o). The beam reflects off the surface of the material and subsequently strikes a phosphorescent screen. Because of the wave-like nature of the electrons, a diffraction pattern characteristic of the first few atomic layers is observed on the screen if the surface is flat and the material is crystalline. With a distance between atomic planes of d = 5 Å, a glancing angle of 1^o, and an operating de Broglie wavelength for the electrons of 2dsinθ, compute the electron energy employed in the technique.