We celebrate the #NationalScienceDay2021 commemorating the discovery of the #RamanEffect. Catch the day’s programme from #BARC, Mumbai: https://www.youtube.com/watch?v=O2GIXOOGBvk
Light has a certain probability of being scattered by any material and most of the scattered photons have the same energy after scattering, an effect called the elastic scattering or Rayleigh Scattering. A smaller fraction of photons may scatter inelastically, where the interaction with the material changes their energy. This inelastic scattering is known as Raman Scattering and the phenomenon is termed as the Raman Effect, in honour of Sir Chandrasekhara Venkata Raman, who first discovered it on this day in 1928.
The inelastically scattered photons carry important information about the vibrational-rotational frequencies of the material and hence its structure. However, the effect is very weak – one photon is Raman scattered against approximately ten million Rayleigh scattered photons. This large background of elastically scattered photons makes it extremely difficult to detect the inelastically scattered photon. The credit for the discovery goes to Sir C. V. Raman and his student Dr. K. S. Krishnan who first observed it even without proper spectroscopic instruments.
Sir C. V. Raman was awarded the Nobel Prize in Physics in 1930 for this discovery.
Raman effect is used to study materials by performing various forms of #RamanSpectroscopy. An important advantage of Raman Spectroscopy is that the incident photons do not have to be in resonance with the vibrational frequency of the material unlike any other spectroscopic technique. In 1998, the Raman effect was designated a National Historic Chemical Landmark by the American Chemical Society in recognition of its significance as a tool for analyzing the composition of liquids, gases, and solids.
