spectrophotometry

spectrophotometry

Branch of spectroscopy dealing with measurement of radiant energy transmitted or reflected by a body as a function of wavelength. The measurement is usually compared to that transmitted or reflected by a system that serves as a standard. In chemistry and physics, different types of spectrophotometers cover wide ranges of the electromagnetic spectrum: ultraviolet (UV), visible light, infrared (IR), or microwave. UV spectrophotometry is particularly useful in detecting and quantifying colourless substances in solution. IR spectrophotometry is used mostly to study the molecular structures of complex organic compounds. In astronomy and astrophysics, spectrophotometric studies also include the X-ray and gamma ray ranges of the spectrum. See also colorimetry.

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spectrophotometry [¦spek·trō·fə′täm·ə·trē]

(analytical chemistry)

A method of chemical analysis based on the absorption or attenuation by matter of electromagnetic radiation of a specified wavelength or frequency. The radiation interacts with specific features of the molecular species being determined, such as the vibrational or rotational motions of the chemical bonds. The radiation can also interact with specific atoms or the whole molecule, for example, by causing the molecule to change its electronic energy state.