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Raman, Sir Chandrasekhara (Venkata)

scattered light indian physics

[rah man] (1888–1970) Indian physicist: showed that light scattered by molecules will show lower and higher frequency components (the Raman effect).

Raman gained a distinguished first class honours degree from Madras, but the lack of scientific opportunities in India prevented him then starting a career as a physicist. Instead he worked as an auditor in the Indian Civil Service for 10 years, continuing his research in his leisure time. The work he produced in sound and on diffraction secured him the professorship of physics at Calcutta. During his time there (1917–33) he discovered the Raman effect (1928), established the Indian Journal of Physics (1926), became president of the Indian Science Congress, was knighted (1929) and received the 1930 Nobel Prize for physics (the first awarded to an Asian). He had an important influence in building up the study of physics in India.

Viewing the blue colour of the Mediterranean Sea in 1921 he thought that explanations of sky colour in terms of light being scattered by suspended particles or molecules were inadequate. Raman showed that light is scattered by molecules in dust-free air and liquids and that the scattered light contains wavelengths not present in the primary monochromatic beam. Light is generally scattered by molecules in solids, liquids or gases, lower and higher frequency components being added as the molecular bonds absorb or impart energy to the deflected photons (the Raman effect).

Raman’s discovery led to one of the earliest confirmations of quantum theory, and also gave a powerful method of analysing molecular structure (Raman spectroscopy).

Interest in the method has heightened in recent years: tuneable lasers and refined photomultipliers give better spectra, and allow even transient molecular structures to be examined.

Ramey, Estelle R. [next] [back] Ramón y Cajal, Santiago

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