GLOSSARY: Spectroscopy

Spectroscopy was originally the study of the interaction between radiation and matter as a function of wavelength. Historically, spectroscopy referred to the use of visible light dispersed according to its wavelength, e.g. by a prism. Later the concept was expanded greatly to comprise any measurement of a quantity as a function of either wavelength or frequency. Thus, it also can refer to a response to an alternating field or varying frequency.