C. V. Raman won the 1930 Nobel Prize in Physics for discovering the light-scattering effect now called the Raman effect.
Raman and his collaborator K. S. Krishnan reported the phenomenon in 1928. When light passes through a transparent material, most of it scatters without changing frequency, but a very small portion changes frequency because it exchanges energy with molecular vibrations.
Those shifted spectral lines provide a chemical fingerprint. Raman spectroscopy is now used to identify minerals, pharmaceuticals, pigments, semiconductors, and biological materials, often without destroying the sample.
Raman was the first Asian scientist to receive a Nobel Prize in a scientific discipline. The effect is named after him, while the related experimental technique is called Raman spectroscopy. It should not be confused with the Compton effect, another form of frequency-shifted scattering involving X-rays and electrons.