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A Blast From the Sub-Continent : Sir Cv Raman , Nobel Laurate and the Raman Effect

An Air Warrior and Post Graduate in Physics who has the Technical expertise to write on pure sciences.

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Introduction

During the colonial age there was not much research carried out by the nations that were enslaved. Generally, research in pure sciences like physics and chemistry was confined to the so called developed world which had all the facilities. In this atmosphere all credit must go to an Indian scientist Sir CV Raman from Bangalore who propounded a new theory in spectroscopy that has come to be known as the Raman Effect. His work was in the field of scattering of light.

The Imperial government recognized his achievements and he was in 1924 made a Fellow of the Royal Society(FRS) as well as knighted by the king in 1929. He won the Nobel Prize for Physics in 1930. He was the second Indian to win the Nobel prize with Rabindra Tagore having won it for literature in 1913.

His birth took place at Tiruchirappalli in Southern India on November 7th, 1888and passed away in 1970.

His research in the field of “Molecular Diffraction of Light” and his observations published in 1922 impressed the scientific community and named the discovery after him. It is known as the "Raman Effect."

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Raman Effect

The diagram given above will give the reader an idea of what the Raman effect is. Raman's main field of research was optics and he carried out years of study and research in this field. Raman passed beams of light through various mediums like liquid's, gases, and solids and observed the light which was a single beam once it emerged from the mediums became a spread with various wavelengths and frequencies. This was because of the action of the molecules through which the light ray was beamed.

Raman was able to correlate the data and finally concluded that once a light was passed through a medium it's wavelength changed. This is a very important property and though at that time scientists could not understand its importance yet now we know that this is one of the very significant discoveries of the 20th century.

This change in wavelength of the light beam that passes through a medium is known as the Raman Effect.

When the light passes through the medium the molecules come into action and the light ray which maybe a single beam is split up into a number of beams with different frequencies. If these frequencies are measured one can get an idea of the property of the medium through which the beam has passed. Sir CV Rahman after a study and measurement of frequencies in thousands of experiments put forward his hypothesis in 1922, after he had just returned from England in 1921.

His theoretical paper was accepted by the Royal Society and all other scientific groups around the world. Another significant aspect was that the Raman effect did not have much of an effect when passed through a gaseous medium. It was strongest when it was passed through solids and to a lesser extent through liquid's. This is because gases have a low density of molecules and cannot diffuse the light.

The property of changing wavelength of a light beam which may be photons etc through solids is the essence of the Raman effect.



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Practical uses

The term 'Raman Spectroscopy' was coined to refer to that branch of physics the door to which had been opened by CV Raman with his observation of the Raman Effect. At that time the Raman effect was treated as a matter of pure physics and one thought it would not have any practical application. Science however is not static and years after his discovery, its application to scanners has made an appearance.

These have been termed as Raman Scanners and are hand held and portable. The scanners are light weight and form a part of the equipment of police and drug squads all over the world. Due their property of detecting wavelength in solids and amorphous substances they are extremely potent in the detection of illegal drugs and narcotics. US narcotic squads and airport police all over the world use these scanners to detect drug smuggling at airports and border check-posts.

.There have been further developments and the Raman scanners are now used even to detect explosives which could be carried by terrorists due to their peculiar property of analyzing the frequency of light rays that emanate from a object. The security experts can easily find out the type of explosive being carried by a terrorist.

The scanners make use of the Raman effect. They beam a ray of light at an object and as it emerges it forms a spread and the wavelengths give a clear indication of the substance carried. Computer analyzers are at hand and the results are available in real time. The Raman Effect has very important applications in the modern age.

Lady Raman in England

Lady Raman in England

Last word

No article on Sir CV Roman would be complete without a reference to his family. As well the practice at the turn of the last century in India, Siri Rahman entered into an arranged marriage . He married Lokasundari Ammal (1892–1980) on 6 May 1907. She was just 13 years old at that time while Raman was 19. He had one son Venkatraman Radhakrishnan after 22 years of marriage in 1929, who was a famous space scientist. He married Mrs. Francoise-Dominique Barnard. They have a son Vivek Radhakrishnan.

Further Reading

The Raman Effect: A Unified Treatment of the Theory of Raman Scattering by Derek A Long- ISBN: 978-0-471-49028-9 May 2002.

Introduction to the Theory of the Raman Effect by JA Koningston- Carleton University, Ottawa.

CV Raman: A Biography by Uma Parmeswaran 2011

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