Ultraviolet-Visible Spectroscopy (UV-Vis)

UV-Vis Spectroscopy is an optical technique that measures change in UV and visible light intensity upon interaction with matter as a function of the wavelength.  UV-Vis spectroscopy mostly probes electron transitions. Typical examples are: transitions from π and n orbitals to anti-bonding π* and σ* orbitals in conjugated organic molecules; d-d transitions in transition metal ions; charge transfer transitions in some organic and transition metal compounds; band gap transitions in semiconductors.

How it works — In a traditional transmittance geometry, a collimated beam of monochromatic light passes through a sample. The intensity I of the transmitted light is measured and compared with the reference intensity I0. A ratio I/I0 as a function of the wavelength is the result of the measurement (UV-Vis spectrum).  In many cases the light absorption in a material is proportional to the concentration of absorbing molecules. This phenomenon is formalized in the Bouguer-Lambert-Beer (or Beer-Lambert) law. It is the basis for using UV-Vis spectroscopy for quantitative analysis.

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Instrumentation Available

Key Attributes

  • UV wavelength range: 190-400 nm, visible range: 400-700 nm, NIR range: 700-2500 nm. Refer to description of a specific instrument for available wavelength range.
  • Typically room temperature measurements.
  • Testing of a broad range of materials – solids, liquids, and gases – depending on the accessories available.
  • A range of measurement geometries are possible, including transmittance, reflectance, scattering.


  • Fast sample analysis
  • Non-destructive technique
  • Relatively small sample size
  • Quantitative analysis possible
  • Well developed mature technique; a variety of instruments and accessories are commercially available
  • Clear physical meaning of the results


  • No direct information about structure
  • Relatively low sensitivity


  • Quantitative analysis
  • Kinetics of chemical reactions
  • Band gap measurements

Additional Reading