Raman spectroscopy is a technique to study vibrational, rotational, and other low-frequency modes e.g. in optical materials. It relies on inelastic scattering of monochromatic light (UV to IR). The laser light interacts with e.g. impurities in the optical materials resulting in an energy shift of the photons, up or down, providing information about the phonon modes in the system.

In this example we used Raman spectroscopy to measure the H2 content in optical materials (see below).