Sir Chandrasekhara Venkata Raman (7 November 1888 – 21 November 1970) was an Indian physicist born in the former Madras Province in India, who carried out ground-breaking work in the field of light scattering, which earned him the 1930 Nobel Prize for Physics. He discovered that when light traverses a transparent material, some of the deflected light changes in wavelength. This phenomenon, subsequently known as Raman scattering, results from the Raman effect. In 1954, India honoured him with its highest civilian award, the Bharat Ratna.
Raman’s father initially taught in a school in Thiruvanaikaval, became a lecturer of mathematics and physics in Mrs. A.V. Narasimha Rao College, Visakhapatnam in the Indian state of Andhra Pradesh, and later joined Presidency College in Madras.
In 1917, Raman resigned from his government service after he was appointed the first Palit Professor of Physics at the University of Calcutta. At the same time, he continued doing research at the Indian Association for the Cultivation of Science (IACS),Calcutta, where he became the Honorary Secretary. Raman used to refer to this period as the golden era of his career.
On 28 February 1928, Raman led experiments at the IACS with collaborators, including K. S. Krishnan, on the scattering of light, when he discovered what now is called the Raman effect. A detailed account of this period is reported in the biography by G. Venkatraman. It was instantly clear that this discovery was of huge value. It gave further proof of the quantum nature of light. Raman had a complicated professional relationship with K. S. Krishnan, who surprisingly did not share the award, but is mentioned prominently even in the Nobel lecture.
Raman spectroscopy came to be based on this phenomenon, and Ernest Rutherford referred to it in his presidential address to the Royal Society in 1929. Raman was president of the 16th session of the Indian Science Congress in 1929. He was conferred a knighthood, and medals and honorary doctorates by various universities.
He was the first Asian and first non-white to receive any Nobel Prize in the sciences. Before him Rabindranath Tagore (also Indian) had received the Nobel Prize for Literature in 1913.
Raman and Suri Bhagavantam discovered the quantum photon spin in 1932, which further confirmed the quantum nature of light.
Raman also worked on the acoustics of musical instruments. He worked out the theory of transverse vibration of bowed strings, on the basis of superposition velocities. He was also the first to investigate the harmonic nature of the sound of the Indian drums such as the tabla and the mridangam. He was also interested in the properties of other musical instruments based on forced vibrations such as the violin. He also investigated the propagation of sound in whispering galleries. Raman’s work on acoustics was an important prelude, both experimentally and conceptually, to his later work on optics and quantum mechanics.
Raman and his student, Nagendra Nath, provided the correct theoretical explanation for the acousto-optic effect (light scattering by sound waves), in a series of articles resulting in the celebrated Raman–Nath theory. Modulators, and switching systems based on this effect have enabled optical communication components based on laser systems.
He also started the company called Travancore Chemical and Manufacturing Co. Ltd. (now known as TCM Limited) which manufactured potassium chlorate for the match industry in 1943 along with Dr. Krishnamurthy. The Company subsequently established four factories in Southern India. In 1947, he was appointed as the first National Professor by the new government of Independent India.
In 1948, Raman, through studying the spectroscopic behaviour of crystals, approached in a new manner fundamental problems of crystal dynamics. He dealt with the structure and properties of diamond, the structure and optical behaviour of numerous iridescent substances (labradorite, pearly feldspar, agate, opal, and pearls). Among his other interests were the optics of colloids, electrical and magnetic anisotropy, and the physiology of human vision.
Raman retired from the Indian Institute of Science in 1948 and established the Raman Research Institute in Bangalore, Karnataka, a year later. He served as its director and remained active there until his death in 1970, in Bangalore, at the age of 82.