Which phenomenon deals with the scattering of light by molecules of a medium when they are excited to vibrational energy levels?

The correct answer is Raman Effect.

Key Point

• Raman Effect:
  • It states that there is a change in the wavelength of light that occurs when a light beam is deflected by molecules.  
  • This is caused due to the molecules of gases, liquids, or solids when they are excited to vibrational energy levels. 
  • The Raman Effect is the phenomenon of scattering of light by molecules present in a medium.​ Hence, Option 3 is correct.
  • When a beam of light travels through a transparent object, a small fraction of the light gets scattered in directions other than where it should.
  • The scattering occurs due to the difference in wavelength of light as it enters into the medium.
  • The Raman effect is defined as the scattering of photons by the excited molecules that are at higher energy levels.
  • Raman effect is also known as Raman scattering.
  • Raman effect, change in the wavelength of light that occurs when a light beam is deflected by molecules.
  • 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.
  • A small part, however, has wavelengths different from that of the incident light its presence is a result of the Raman effect.