The Raman effect was first discovered in 1928 by the Indian physicist C.V. Raman. Widespread use of this type of spectroscopy had been limited due to its earlier high instrumentation costs. In the past, excitation light sources had been the main reason for these high costs. In the last few years, this situation has changed and m·u·t now provides low-cost miniaturized Raman spectrometers customized to application needs.

Raman spectroscopy provides information about molecular vibrations and can therefore be used for sample identification as well as for quantization. The technology is based on the measurement of scattered light from a sample and the spectrum is interpreted similar to an infrared absorption spectrum. The sample is illuminated with a monochromatic light source such as a laser.

The majority of the scattered light is of the same frequency as the excitation source, known as the Rayleigh scattering. A very small amount of the light (approx. 10-5% of the excitation light intensity) is shifted in energy from the laser frequency, known as Raman lines.
The shift is due to the interaction between the incident electromagnetic waves and the vibration energy level of the sample molecules. These spectra are plotted with respect to the laser frequency such that the Rayleigh band lies at 0 cm^-1.

The Raman spectrum is used for qualitative as well as for quantitative analysis. As these spectra are very specific, they can easily be used for searches against a database for sample identification. And the band areas give the quantitative information. Compared to the used IR absorption spectroscopy, Raman spectra are easier to analyze as they are sharper and smoother.