Sir Chandrasekhara Venkata Raman(C. V. Raman)

     Sir Chandrasekhara Venkata Raman(C. V. Raman)

                              

C.V . Raman was born on 7 November 1888  in Tiruchirapalli, Madras Presidency, British India to Hindu Tamil Brahmin parents Chandrasekhara Ramanathan Iyer and Parvathi Ammal. He was the second of eight siblings. His father was a teacher at a local high school, and earned a modest income. In 1892, his family moved to Vishakapatnam,  in Andhra Pradesh as his father was appointed to the faculty of physics at Mrs A.V. Narasimha Rao College. 

Education details:

There Raman studied at St Aloysius' Anglo-Indian High School. He passed matriculation at age 11 and the First Examination in Arts examination  with a scholarship at age 13, securing first position in both under the Andhra Pradesh school board  examination. In 1904, he obtained a B.A. degree from the University of Madras, where he stood first and won the gold medals in physics and English. At age 18, while still a graduate student, he published his first scientific paper on "Unsymmetrical diffraction bands due to a rectangular aperture" in the British journal "Philosophical Magazine" in 1906. He earned an M.A. degree from the same university with highest distinction in 1907. His second paper published in the same journal that year was on surface tension of liquids.

Career:

Raman followed suit and qualified for the Indian Finance Service achieving first position in the entrance examination in February 1907.He was posted in Calcutta  as Assistant Accountant General in June 1907. Raman's article "Newton's rings in polarised light" published in Nature in 1907 became the first from the institute. The work inspired IACS to publish a journal, Bulletin of Indian Association for the Cultivation of Science, in 1909 in which Raman was the major contributor.

 In 1909, Raman was transferred to Rangoon, British Burma , to take up the position of currency officer. After only a few months, he had to return to Madras as his father died from an illness. The subsequent death of his father and funeral rituals compelled him to remain there for the rest of the year. Soon after he resumed office at Rangoon, he was transferred back to India at Nagpur, Maharashtra, in 1910. Even before he served a year in Nagpur, he was promoted to Accountant General in 1911 and again posted to Calcutta.

From 1915, the University of Calcutta started assigning research scholars under Raman at IACS. Sudhangsu Kumar Banerji , a PhD scholar under Ganesh Prasad, was his first student. From the next year, other universities followed suit including University of Allahabad, Rangoon University, Queen's College Indore, Institute of Science, Nagpur, Krisnath College, and University of Madras. By 1919, Raman had guided more than a dozen students.  Following Sircar's death in 1919, Raman received two honorary positions at IACS, Honorary Professor and Honorary Secretary. He referred to this period as the "golden era" of his life.

 

Raman was chosen by the University of Calcutta to become the Palit Professor of Physics, a position established after the benefactor Sir Taraknath Palit, in 1913. The university senate made the appointment on 30 January 1914, as recorded in the meeting minutes:

 

Scientific Contributions:

Musical sound:

Raman also studied the uniqueness of Indian drums. His analyses of the harmonic nature of the sounds of tabla and mridangam were the first scientific studies on Indian percussions. He wrote a critical research on vibrations of the pianoforte string that was known as Kaufmann's theory. During his brief visit of England in 1921, he managed to study how sound travels in the Whispering Gallery of the dome of St Paul's Cathedral in London that produces unusual sound effects. His work on acoustics was an important prelude, both experimentally and conceptually, to his later works on optics and quantum mechanics.

 

Blue colour of the sea:

Raman, in his broadening venture on optics, started to investigate scattering of light starting in 1919. His first phenomenal discovery of the physics of light was the blue colour of seawater. During a voyage home from England on board the S.S. Narkunda in September 1921, he contemplated the blue colour of the Mediterranean Sea. Using simple optical equipment, a pocket-sized spectroscope and a Nicol prism in hand, he studied the seawater. Of several hypotheses on the colour of the sea propounded at the time, the best explanation had been that of Lord Rayleigh's in 1910, according to which, "The much admired dark blue of the deep sea has nothing to do with the colour of water, but is simply the blue of the sky seen by reflection". Rayleigh had correctly described the nature of the blue sky by a phenomenon now known as Rayleigh scattering, the scattering of light and refraction by particles in the atmosphere.

 

Raman effect:

The scattering experiments--

 

Krishnan started the experiment in the beginning of January 1928  On 7 January, he discovered that no matter what kind of pure liquid he used, it always produced polarised fluorescence within the visible spectrum of light. As Raman saw the result, he was astonished why he never observed such phenomenon all those years. That night he and Krishnan named the new phenomenon as "modified scattering" with reference to the Compton effect as an unmodified scattering. On 16 February, they sent a manuscript to Nature titled "A new type of secondary radiation", which was published on 31 March.

On 28 February 1928, they obtained spectra of the modified scattering separate from the incident light. Due to difficulty in measuring the wavelengths of light, they had been relying on visual observation of the colour produced from sunlight through prism. Raman had invented a type of spectrograph for detecting and measuring electromagnetic waves. Referring to the invention, Raman later remarked, "When I got my Nobel Prize, I had spent hardly 200 rupees on my equipment," although it was obvious that his total expenditure for the entire experiment was much more than that. From that moment they could employ the instrument using monochromatic light from a mercury arc lamp which penetrated transparent material and was allowed to fall on a spectrograph to record its spectrum. The lines of scattering could now be measured and photographed.

 

Awards:

*Fellow of the Royal Society (1924)
*Matteucci Medal (1928)
*Knight Bachelor (1930)
*Hughes Medal (1930)
*Nobel Prize in Physics (1930)
*Bharat Ratna (1954)
*Lenin Peace Prize (1957)

Death:

At the end of October 1970, Raman had a cardiac arrest and collapsed in his laboratory. He was moved to the hospital where doctors diagnosed his condition and declared that he would not survive another four hours.He however survived a few days and requested to stay in the gardens of his institute surrounded by his followers .He died from natural causes early the next morning on 21 November 1970 at the age of 82.