This effect was discovered by sir C.V. Raman; hence the name.
The elastic scattering, the commonly observed and most of the photons undergo this, is also called Rayleigh scattering. In this the scattered photons have the same energy (frequency and wavelength) as the incident photons. But a small fraction of the scattered photons have a different wavelength and frequency. Normally such photons have less frequency (greater wavelength) than the incident photons.
Sir C.V. Raman, the Indian physicist whose work was influential in the growth of science in India was born on 7 November 1988. He was the recipient of the Nobel Prize for Physics in 1930 for the discovery that when light traverses a transparent material, some of the deflected light changes in wavelength. This phenomenon is now called Raman scattering and is the result of the Raman effect.
Venkata Raman was born in Thiruvanaikaval, Trichinopoly, Madras Presidency, in British India to R. Chandrasekhara Iyer (b. 1866) and Parvati Ammal (Saptarshi Parvati).
His father was a lecturer in mathematics and physics at Presidency College in Madras, which Raman entered in 1902 at the age of 13. In 1904 he passed his B.A. examination in first place and won the gold medal in physics, and in 1907 he gained his M.A. degree with the highest distinctions.
Get more details at http://en.wikipedia.org/wiki/C._V._Raman