What is the ‘Raman effect’? "EMPOWER IAS"

In news:

• February 28^th was celebrated as National Science Day. In 1986, the Govt. of India designated this Day, to commemorate the announcement of the discovery of the “Raman effect”.

 

National Science Day

• Every year on February 28, India celebrates National Science Day to mark the discovery of Raman Effect by Sir C V Raman.
• Raman Effect was discovered by the professor on February 28, 1928.
• This year, the National Science Day is celebrated under the theme.
• Theme: Women in Science
• The National Science Day was first designated in 1986 and was first celebrated in 1987.
• Sir C V Raman announced his discovery on this day. He was later awarded the Nobel Prize for this discovery in 1930.
• It was the National Council for Science and Technology that asked the GoI to pronounce February 28 as the National Science Day.
• The Council operates under Department of Science and Technology and is the nodal agency in implementing the celebrations of the day.

 

 

CV Raman

• Raman conducted his Nobel-prize winning research at IACS, Calcutta.
• While he was educated entirely in India, Raman travelled to London for the first time in 1921, where his reputation in the study of optics and acoustics was known to physicists such as JJ Thomson and Lord Rutherford.
• The Raman Effect won scientist Sir CV Raman the Nobel Prize for physics in 1930.
• It was also designated as an International Historic Chemical Landmark jointly by the American Chemical Society (ACS) and the Indian Association for the Cultivation of Science (IACS).
• His speciality was the study of vibrations and sounds of stringed instruments such as the Indian veena and tambura, and Indian percussion instruments such as the tabla and mridangam.

 

What is Raman Effect?

• Some part of light beam after passing through a transparent medium gets scattered.
• This phenomenon of scattering of light is termed as Raman Scattering and the cause of scattering is called the Raman Effect.
• The wavelength of these scattered rays is different from that of the incident rays of light.
• Thi phenomenon was explained/discovered by Indian physicist Chandrasekhara Venkata Raman (CV Raman) on February 28, 1928.
• This discovery was awarded with the Nobel Prize in Physics in 1930.
• Feb 28 is observed as National Science Day in India.

 

 

Observing the effect

• The Raman Effect is when the change in the energy of the light is affected by the vibrations of the molecule or material under observation, leading to a change in its wavelength.
• Significantly, it notes that the Raman effect is “very weak” — this is because when the object in question is small (smaller than a few nanometres), the light will pass through it undisturbed.
• But a few times in a billion, light waves may interact with the particle. This could also explain why it was not discovered before.
• In general, when light interacts with an object, it can either be reflected, refracted or transmitted.
• One of the things that scientists look at when light is scattered is if the particle it interacts with is able to change its energy.

 

Applications

• Raman spectroscopy is used in many varied fields – in fact, any application where non-destructive, microscopic, chemical analysis and imaging is required.
• Whether the goal is qualitative or quantitative data, Raman analysis can provide key information easily and quickly.
• It can be used to rapidly characterize the chemical composition and structure of a sample, whether solid, liquid, gas, gel, slurry or powder.