spectroscopy
Spectroscopy, or spectrometry, is the experimental study of the spectrum of a physical phenomenon, that is to say, its decomposition on an energy scale, or any other quantity corresponding to an energy. Historically, this term applied to the decomposition, for example by a prism, of the visible light emitted or absorbed by the object to be studied. Today, this principle is expressed in a multitude of specialized experimental techniques which find applications in almost all fields of physics in the broad sense: astronomy, biophysics, chemistry, atomic physics, plasma physics, nuclear physics, solid physics , mechanical, acoustic, etc. Spectroscopy not only analyzes visible light but also electromagnetic radiation in all frequency ranges, elastic waves such as sound or seismic waves, or particles. In general, the measuring instrument for obtaining a spectrum is called a spectrometer or a spectroscope.