The monochromator is an important component of the UV/Vis spectrophotometer that will allow you to select the appropriate wavelength for your experiment. Certain monochromator features, such as the type of mounting and dispersive element used, can have an impact on resolution and accuracy, so it is important to choose the most suitable options for your application.
Prism vs. Diffraction Grating
The dispersive element of the monochromator is what breaks the beam of light that enters through the entrance slit down into separate wavelengths, and the wavelength that exits through the exit slit can be adjusted by rotation of the dispersive element. The two main types of dispersive elements are prisms and diffraction gratings; diffraction gratings are more commonly used in modern spectrophotometers. This is because gratings are made up of several angled grooves that provide consistent linear dispersion throughout the UV and visible range, while the non-linear dispersion of a prism will cause resolution to diminish as wavelengths approach the red and infrared domain.1
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