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UPSC Combined Geo-Scientist

Chemist

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

Mains Paper I covers inorganic chemistry.

UPSC Combined Geo-Scientist, Mains · 2019 · Mains Paper I

Q9(a). Cerium absorption bands

Question

The absorption band of cerium(III) is broad, while that of other lanthanides is sharp. Explain.

Answer in brief

The characteristic Ce(III) absorption involves allowed 4f→5d excitation; most familiar sharp lanthanide bands are shielded 4f→4f transitions.

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CoversCerium absorption bandsLanthanide spectroscopy

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