National Science Day: Remembering Prof. C. V. Raman

C.V. Raman, in full Sir Chandrasekhara Venkata Raman, born on November 7, 1888, Trichinopoly, India and died November 21, 1970, Bangalore, 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. He discovered that when light interacts with a molecule the light can donate a small amount of energy to the molecule. As a result of this, the light changes its colour and the molecule vibrates. The change of colour can act as a ‘fingerprint’ for the molecule.National Science Day is celebrated every year on February 28 to commemorate the discovery of Raman Effect by CV Raman on this day in 1928.

His father was a lecturer in mathematics and physics so that from the first he was immersed in an academic atmosphere.He entered Presidency College, Madras, in 1902, and in 1904 passed his B.A. examination, winning the first place and the gold medal in physics. 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.

Raman made his first trip to London in 1921 to collaborate on a study with two internationally famous British scientists — J J Thomson and Lord Rutherford.His return journey to India — a fifteen-day voyage by ship, would be a historic one. Raman was struck by a question while cruising the deep blue Mediterranean waters: Why does the sea appear blue? At the time, there was one explanation for it already, but one that Raman wasn’t convinced by. Lord Rayleigh, a British scientist who made countless contributions to theoretical and experimental physics, explained that the colour of sea simply reflected the colour of the sky. Raman outlined his thoughts on why he didn’t agree with Rayleigh’s theory and posted a letter to the journal Nature once his ship docked in the Bombay harbour.Studying 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 the energies associated with transitions between different rotational and vibrational states in the scattering material.

Educated entirely in India, C V Raman’s expertise were acoustic vibrations, sounds of string instruments like the violin, the veena and two signature Indian percussion instruments — the tabla and mridangam.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 he 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). He was the uncle of Subrahmanyan Chandrasekhar, who won the 1983 Nobel Prize for Physics, with William Fowler.