A type of scattering of electromagnetic radiation in which light suffers a change in frequency and a change in phase as it passes through a material medium. The intensity of Raman scattering is about one-thousandth of that in Rayleigh scattering in liquids; for this reason it was not discovered until 1928. However, it was not until the development of the laser that the effect was put to use.
In Raman spectroscopy light from a laser is passed through a substance and the scattering is analysed spectroscopically. The new frequencies in the Raman spectrum of monochromatic light scattered by a substance are characteristic of the substance. Both inelastic and superelastic scattering occurs. The technique is used as a means of determining molecular structure and as a tool in chemical analysis. The effect was discovered by the Indian scientist Sir C. V. Raman (1888–1970).
http://www.uky.edu/~holler/raman.html The original paper by Raman and Krishnan
Subjects: Chemistry — Physics.