Ultraviolet and visible spectroscopy is mainly used to identify compounds with conjugated double bonds.

When light passes through a particle, it will absorb either ultraviolet or visible light based on the energy required for transitioning electrons from the initial or ground state to a higher energy excited state.

The ultraviolet or UV spectrum is obtained if the molecule absorbs light between the wavelengths of 180 to 400 nanometers, whereas a visible spectrum is obtained if the absorption occurs between 400 to 780 nanometers.

Since the energy of the radiation is inversely proportional to wavelength, ultraviolet radiation with shorter wavelengths have greater energy than visible light.

UV and visible spectroscopy are used to identify compounds in quantitative analysis by comparing their absorbance values with those of known compounds.