Luminescence studies are central to an extensive range of disciplines, both as a primary experiment and in a minor role for additional discrimination between samples. The sensitivity of luminescence measurements is ideal for studies of the electronic structure of solids, crystalline defects, and impurities. These measurements identify and separate properties of the intrinsic lattice (and defects), contaminants, dopants (trace elements), or secondary inclusions with detection limits frequently well below parts per million. When a high spectral resolution is applied, one can further identify more subtle changes, including stress, location of an ion within the unit cell, or the charge state of impurity.

While the high sensitivity to the local environment is a significant strength of luminescence techniques, a direct consequence is that there is a wide range of mechanisms that can lead to contrast in a cathodoluminescence (CL) map or a peak in a luminescence spectrum. In the following sections, we provide an introduction to interpreting CL data based on the sample type and methods available.