A classroom demonstration of reciprocal space

An array of nanowires and a laser pointer are used for a simple visualization of two-dimensional reciprocal space. The experiment can be performed without any preparation and in any classroom. It aids the teaching of scattering experiments, and illustrates the underlying principles of electron, x-ray, and neutron scattering. A detailed study of the diffraction pattern was performed by mounting the sample with nanowires on a stage designed for x-ray scattering. The setup is well suited for undergraduate students, who get training in sample alignment in a small lab instead of at a large-scale facility. The exact positions of the diffraction spots are calculated and monitored experimentally for a 360° rotation of the sample. By fitting to this set of images, it is possible to determine the lattice vectors of the artificial crystal with an uncertainty of less than 1%.