A proper understanding of the Davisson and Germer experiments for undergraduate modern physics course

The physical interpretation for the Davisson-Germer experiments on nickel (Ni) single crystals [(111), (100), and (110) surfaces] is presented in terms of two-dimensional (2D) Bragg scattering. The Ni surface acts as a reflective diffraction grating when the incident electron beams hits the surface. The 2D Bragg reflection occurs when the Ewald sphere intersects the Bragg rods arising from the two-dimension character of the system. Such a concept is essential to proper understanding of the Davisson-Germer experiment for undergraduate modern physics course.