The Raman Effect !

Sir Chandrasekhara Venkata Raman, born on November 7, 1888, Trichinopoly, was an Indian physicist whose work was influential in the growth of science in India. 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 light that is deflected changes in wavelength. This phenomenon is now called Raman scattering and is the result of the Raman effect.

After earning a master’s degree in physics at Presidency College, University of Madras, in 1907, Raman became an accountant in the finance department of the Indian government. He became professor of physics at the University of Calcutta in 1917. He Studied the scattering of light in various substances, in 1928 he found that when a transparent substance is illuminated by a beam of light of one frequency, a small portion of the light emerges at right angles to the original direction, and some of this light is of different frequencies than that of the incident light. These so-called Raman frequencies are equal to the infrared frequencies for the scattering material and are caused by the exchange of energy between the light and the material.

Raman was knighted in 1929, and in 1933 he moved to the Indian Institute of Science, at Bangalore, as head of the department of physics. In 1947 Raman was named director of the Raman Research Institute there and in 1961 became a member of the Pontifical Academy of Science. He contributed to the building up of nearly every Indian research institution in his time, founded the Indian Journal of Physics and the Indian Academy of Sciences, and trained hundreds of students who found important posts in universities and government in India and Myanmar (Burma).

RAMAN SCATTERING:-

Raman scattering or the Raman effect is the inelastic scattering of a photon. It was discovered by Sir C. V. Raman and K. S. Krishnan in liquids,and by Grigory Landsberg and Leonid Mandelstam in crystals.

When light is scattered from an atom or molecule, most photons are elastically scattered (Rayleigh scattering), such that the scattered photons have the same energy and wavelength as the incident photons. However, a small fraction of the scattered light (approximately 1 in 10 million photons) is scattered by an excitation, with the scattered photons having a frequency different from, and usually lower than, the frequency of the incident photons.In a gas, Raman scattering can occur with a change in vibrational, rotational or electronic energy of a molecule. 

In 1922, Indian physicist C. V. Raman published his work on the "Molecular Diffraction of Light," the first of a series of investigations with his collaborators which ultimately led to his discovery (on 28 February 1928) of the radiation effect which bears his name. The Raman effect was first reported by C. V. Raman and K. S. Krishnan, and independently by Grigory Landsberg and Leonid Mandelstam, in 1928. Raman received the Nobel Prize in 1930 for his work on the scattering of light. In 1998 the Raman effect was designated an ACS National Historical Chemical Landmark in recognition of its significance as a tool for analyzing the composition of liquids, gases, and solids.