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Indian Forest Service (Mains)

Chemistry optional

  • 2 papers
  • 200 marks each
  • 3 h per paper

Paper I covers physical and inorganic chemistry.

Indian Forest Service (Mains), Chemistry optional · 2016 · Paper I

Q5(a)(i). Fluorescence

Question

Explain the following briefly: (i) Fluorescence

Answer in brief

Fluorescence is the emission of light when an excited molecule returns from the lowest excited singlet S₁ to the ground singlet S₀: spin-allowed, fast (within a few nanoseconds), so it stops almost as soon as the exciting light is cut off; the emitted light has a longer wavelength than the absorbed light.

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