Saturday, 4 August 2012

SIR C.V.RAMAN BIOGRAPHY

Sir Chandrasekhara Venkata Raman, (7 November 1888 – 21 November 1970) 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.



Early years :

Venkata Raman was born at Thiruvanaikaval, near Tiruchirappalli, Madras Province, in British India to R. Chandrasekhara Iyer (b. 1866) and Parvati Ammal (Saptarshi Parvati). He was the second of their five children. At an early age, Raman moved to the city of Vizag, Andhra Pradesh. Studied in St.Aloysius Anglo-Indian High School. His father was a lecturer in Mathematics and physics at Presidency College (Madras) which Raman entered in 1902 at the age of 11. 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.

Career :

In 1917, Raman resigned from his government service and took up the newly created Palit Professorship in Physics at the University of Calcutta. At the same time, he continued doing research at the Indian Association for the Cultivation of Science, Calcutta, where he became the Honorary Secretary. Raman used to refer to this period as the golden era of his career. Many students gathered around him at the IACS and the University of Calcutta.


Energy level diagram showing the states involved in Raman signal.

Raman with Richard Bär (1892–1940)

On February 28, 1928, Raman led experiments at the Indian Association for Cultivation of Science with collaborators, including K. S. Krishan, on the scattering of light, when he discovered the Raman effect. A detailed account of this period is reported in the biography by. 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. Krishan, who did not surprisingly 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. Raman was confident of winning the Nobel Prize in Physics as well, and was disappointed when the Nobel Prize went to Richardson in 1928 and to de Broglie in 1929. He was so confident of winning the prize in 1930 that he booked tickets in July, even though the awards were to be announced in November, and would scan each day's newspaper for announcement of the prize, tossing it away if it did not carry the news. He did eventually win the 1930 Nobel Prize in Physics "for his work on the scattering of light and for the discovery of the effect named after him". 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 Bhagavantam discovered the quantum photon spin in 1932, which further confirmed the quantum nature of light.
During his tenure at IISc, he recruited the then talented electrical engineering student, G._N._Ramachandran, who later was a distinguished X-ray crystallographer himself.
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.

Raman and his student, Nagendra Nath, of Mim high school, 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.

In 1934, Raman became the assistant director of the Indian Institute of Science in Bangalore, where two years later he continued as a professor of physics. Other investigations carried out by Raman were experimental and theoretical studies on the diffraction of light by acoustic waves of ultrasonic and hypersonic frequencies (published 1934–1942), and those on the effects produced by X-rays on infrared vibrations in crystals exposed to ordinary light.

He also started a company called cv Chemical and Manufacturing Co. Ltd. in 1943 along with Dr. Krishnamurthy. The Company during its 60 year history, 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 behavior 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 behavior 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.

Personal life :

He was married on 6 May 1907 to Lokasundari Ammal (1892–1980) with whom he had two sons, Chandrasekhar and Radhakrishnan.
On his religious views, he was said to be an agnostic. Raman retired from the Indian Institute of Science in 1944 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.

C.V. Raman was the paternal uncle of Subrahmanyan Chandrasekhar, who later won the Nobel Prize in Physics (1983) for his discovery of the Chandrasekhar limit in 1931 and for his subsequent work on the nuclear reactions necessary for stellar evolution.

Honours and awards :

Raman was honoured with a large number of honorary doctorates and memberships of scientific societies. He was elected a Fellow of the Royal Society early in his career (1924) and knighted in 1929. In 1930 he won the Nobel Prize in Physics. In 1941 he was awarded the Franklin Medal. In 1954 he was awarded the Bharat Ratna. He was also awarded the Lenin Peace Prize in 1957. In 1998, the American Chemical Society and Indian Association for the Cultivation of Science recognized Raman's discovery as an International Historic Chemical Landmark.
India celebrates National Science Day on 28 February of every year to commemorate the discovery of the Raman effect in 1928.

No comments:

Post a Comment