C V Raman

♤ One of the most prominent Indian scientists in history, C.V. Raman was the first Indian person to win the Nobel Prize in physics in 1930 for his ground breaking work in the field of light scattering. It is now commonly known as the "Raman Effect".

♤ He discovered that, when light traverses a transparent material, some of the deflected light changes in wavelength.

♤ In 1954, he was honoured with the highest civilian award in India, the Bharat Ratna.

♤ He was passionate to discover the reason of the blue colour of sky and sea and performed many experiments regarding the scattering of light from water and transparent blocks of ice. According to the results, he established the scientific explanation for the blue colour of sea-water and sky.

♤ What is Raman Effect?

o When a beam of light traverses a dust-free, transparent sample of a chemical compound, a small fraction of the light emerges in directions other than that of the incident (incoming) beam. Most of this scattered light is of unchanged wavelength (and frequencies).

o A small part, however, has wavelengths different from that of the incident light; its presence is a result of the Raman Effect.

o When the emitted photon has lower energy than incident photon it is known as Stokes Raman scattering and when it has higher energy than incident photon it is called Anti-Stokes scattering. This is called Raman Effect or Raman spectroscopy.

♤ Why is Raman spectroscopy important?

o Raman spectroscopy is used to analyze a wide range of materials, including gases, liquids, and solids.

o Highly complex materials such as biological organisms and human tissue can also be analyzed by Raman spectroscopy.

o Raman spectroscopy can be used to determine the force constant and bond length for molecules which can’t be determined with other spectroscopy techniques like rotational spectroscopy, vibrational spectroscopy or electronic spectroscopy.

o It is also used in optical amplifiers to amplify an optical signal directly, without the need to first convert it to an electrical signal.

(The year 2013 was 125th birth anniversary of Dr. C V Raman.)