Difference between UV and visible (UV-Vis) spectroscopy

UV (Ultraviolet) and visible (Vis) spectroscopy are two closely related techniques that together form UV-Vis spectroscopy. The main difference between them lies in the range of wavelengths they cover.

  1. UV Spectroscopy:
    • Wavelength Range: UV spectroscopy involves the measurement of electromagnetic radiation in the ultraviolet region, typically spanning from 190 to 400 nanometers.
    • Information Obtained: UV spectroscopy provides information about electronic transitions within a molecule. It is particularly sensitive to the movement of electrons between different energy levels, such as those involved in pi-electron transitions in conjugated systems.
  2. Visible Spectroscopy:
    • Wavelength Range: Visible spectroscopy covers the range of wavelengths from about 400 to 700 nanometers.
    • Information Obtained: Visible spectroscopy also deals with electronic transitions, but it focuses on transitions involving outer electrons. This technique is particularly useful for studying the color and absorption properties of compounds.
  3. UV-Vis Spectroscopy:
    • Combined Range: UV-Vis spectroscopy, as the name suggests, encompasses both the UV and visible regions, providing a broader wavelength range from 190 to 700 nanometers.
    • Applications: UV-Vis spectroscopy is commonly used for analyzing the absorption of light by molecules, especially organic compounds. It is widely applied in fields such as chemistry, biochemistry, environmental science, and materials science.

UV and visible spectroscopy are components of the broader UV-Vis spectroscopy technique. UV spectroscopy deals with shorter-wavelength ultraviolet light and focuses on electronic transitions involving inner electrons, while visible spectroscopy deals with longer-wavelength visible light and emphasizes transitions involving outer electrons. UV-Vis spectroscopy, by combining both ranges, offers a comprehensive approach for studying electronic transitions in molecules over a wide range of wavelengths.