C. V. Raman

 

Sir Chandrasekhara Venkata Raman :

  7 November 1888 – 21 November 1970) was an Indian FC physicist known for his work in the field of light scattering. Using a spectrograph that he developed, he and his student K. S. Krishnan discovered that when light traverses a transparent material, the deflected light changes its wavelength and frequency. This phenomenon, a hitherto unknown type of scattering of light, which they called "modified scattering" was subsequently termed the Raman effect or Raman scattering. Raman received the 1930 Nobel Prize in Physics for the discovery and was the first Asian to receive a Nobel Prize in any branch of science.

C. V. Raman was born in Tiruchirappalli in the Madras Presidency of British India (now Tiruchirapalli, Tamil Nadu, India) to Iyer Brahmin parents, Chandrasekhar 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. He recalled: "I was born with a copper spoon in my mouth. At my birth my father was earning the magnificent salary of ten rupees per month!"In 1892, his family moved to Visakhapatnam (then Vizagapatam or Vizag) in Andhra Pradesh as his father was appointed to the faculty of physics at Mrs A.V. Narasimha Rao College.

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)

Raman was educated at the St Aloysius' Anglo-Indian High School, Visakhapatnam.He passed matriculation at age 11 and the First Examination in Arts examination (equivalent to today's intermediate examination, pre-university course) with a scholarship at age 13,securing first position in both under the Andhra Pradesh school board (now Andhra Pradesh Board of Secondary Education) examination.

One of Raman's interests was on the scientific basis of musical sounds. He was inspired by Hermann von Helmholtz's The Sensations of Tone, the book he came across when he joined IACS. He published his findings prolifically between 1916 and 1921. He worked out the theory of transverse vibration of bowed string instruments based on superposition of velocities. One of his earliest studies was on the wolf tone in violins and cellos.He studied the acoustics of various violin and related instruments, including Indian stringed instruments, and water splashes. He even performed what he called "Experiments with mechanically-played violins."

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.

Raman effect

Main article: Raman scattering

Background

Raman's second important discovery on the scattering of light was a new type of radiation, an eponymous phenomenon called the Raman effect. After discovering the nature of light scattering that caused blue colour of water, he focused on the principle behind the phenomenon. His experiments in 1923 showed the possibility of other light rays formed in addition to incident ray when sunlight was filtered through a violet glass in certain liquids and solids. Ramanathan believed that this was a case of a "trace of fluorescence."In 1925, K. S. Krishnan, a new Research Associate, noted the theoretical background for the existence of an additional scattering line beside the usual polarised elastic scattering when light scatters through liquid.He referred to the phenomenon as "feeble fluorescence." But the theoretical attempts to justify the phenomenon were quite futile for the next two years.