Introducing the Raman Effect,its Theory and Practical Use

M G Singh By M G Singh, 19th Aug 2013 | Follow this author | RSS Feed | Short URL http://nut.bz/vwzhaizd/
Posted in Wikinut>Guides>Technology>Optics

The Raman effect was initially thought of as an innocuous discovery, but now its use has brought out its potency

Sir CV Raman

Generally research in physics is associated with the developed nations. But in 1928 an Indian scientist from Bangalore, propounded a new theory in spectroscopy that has come to be known as the Raman Effect.

The scientist was Sir Chandrasekhar Venkat Raman (he was knighted for this discovery), propounded a new theory on scattering of light. Subsequently he won the Nobel Prize for physics in 1930.

The Raman Effect

Raman after intensive study at his laboratory in Bangalore concluded, that when a light beam travels through a medium, the beam is deflected by the molecules. But more important he observed that a small part of the emerging light beam after deflection by the molecules had a different wave length from the original beam. In other words the wavelength of light after passing through a medium and being deflected by the molecules had a different wavelength.

This change in wavelength of the light beam is known as the Raman Effect and forms an important part of spectroscopy. The limiting factor for this was that the light had to pass from a dust free medium. He also observed that the entire beam did not have its wavelength changed, but only a small part. A simple schematic diagram as given above will illustrate the Raman Effect

Further Amplification

As can be seen from the diagram the incident light after deflection by the molecules is scattered. Some parts of this scattered light have a different wavelength from the original beam.

The original beam may consist of particles or photons. This beam will have a frequency and on striking a surface it gets scattered. Frequency changes were observed by Raman in some parts of the scattered light.

Generally it is seen that the Raman Effect is feeble in liquids, but it is feebler in gases. Hence the Raman Effect is studied in liquids and solids. Gases have low molecular concentration and scattering of light is dependent on striking molecules. The Raman Effect is low in gaseous medium.

Practical Uses

The science that deals with this change of frequency is referred to as Raman spectroscopy. This discovery at that time appeared of not much use, but now the Raman Effect has tremendous use in a variety of fields.

A development is the hand held scanners called Raman scanners, which weigh just about 300gms. These are used by US narcotics squads and airports to detect drugs. Security experts have concluded that Raman Scanners can also be used to detect explosives being carried by terrorists. Safety inspectors are already using Raman scanners to detect hazardous chemicals and gases. It is also finding use in forensic work.
The principle of these scanners is simple. They detect the molecular structure of the object after the light is beamed. The change of frequency reveals the molecular structure of the scanned object. This is the Raman effect. The results are amplified by lasers to arrive at a conclusion. Thus what appeared an innocuous discovery has assumed great importance.

Tags

Cv Raman, Diffraction Of Light, Raman Effect, Reflection Of Light, Scanners

Meet the author

author avatar M G Singh
A man who spent his early years in Air Force. An avid writer with over 6000 articles and 60 short stories published.Two novels on the anvil for publication.

Share this page

moderator johnnydod moderated this page.
If you have any complaints about this content, please let us know

Comments

author avatar cnwriter..carolina
19th Aug 2013 (#)

I dont quite understand Madan but I do know that this is a most enlightening piece telling us more about the Light and how it works in the kingdom of man...many thanks...

Reply to this comment

author avatar M G Singh
20th Aug 2013 (#)

Thank you Caroline. I am glad you read this post. I simplified it as much as possible.

Reply to this comment

author avatar Sivaramakrishnan A
20th Aug 2013 (#)

This discovery is proving like wine - it gets better over time! Thanks Madan for a clear explanation - siva

Reply to this comment

author avatar M G Singh
20th Aug 2013 (#)

Thank you Shiva. Its great of you to comment

Reply to this comment

author avatar Ptrikha
20th Aug 2013 (#)

A great discovery with great practical usage.

Reply to this comment

author avatar M G Singh
20th Aug 2013 (#)

Thank you ptrikha

Reply to this comment

author avatar Judy Ellen
21st Aug 2013 (#)

I agree! Thank you so much for this detailed explanation for novices like me! This is an amazing discovery that is now used to save lives!

Reply to this comment

author avatar M G Singh
21st Aug 2013 (#)

Thank you Judy for reading it.

Reply to this comment

author avatar Trillionaire
24th Aug 2013 (#)

Thank you.

Reply to this comment

author avatar M G Singh
24th Aug 2013 (#)

Thanks trillionaire

Reply to this comment

author avatar M G Singh
24th Aug 2013 (#)

Thanks trillionaire

Reply to this comment

Add a comment
Username
Can't login?
Password