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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 · 2022 · Paper I

Q6(a). Singlet and triplet excited states

Question

How does a singlet excited state differ from a triplet excited state? Explain with the help of an energy level diagram.

Answer in brief

A singlet has total spin S = 0 and multiplicity 1; a triplet has S = 1 and multiplicity 3. For the same orbital configuration, exchange usually makes the triplet lower in energy.

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Topic notes: photochemistry (quantum yield, Jablonski diagram, H₂–halogen reactions), with every Civil Services, IFoS and Geo-Scientist PYQ →

Coverssinglet and triplet statesJablonski diagramintersystem crossingfluorescencephosphorescence

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