Question

The UV-visible absorption bands in the spectra of lanthanoid ions are ‘X’, probably because of the excitation of electrons involving ‘Y’. The ‘X’ and ‘Y’, respectively, are :

• A. Broad and f orbitals
• B. Narrow and f orbitals
• C. Broad and d and f orbitals
• D. Narrow and d and f orbitals

Answer 1

The Correct Option is B

Lanthanides have narrow absorption bands in the UV-visible region of the spectrum. This is because the f orbitals are shielded effectively by the outer electrons, so the electronic transitions within the \(f\) orbitals are less affected by the external environment (ligands or other ions). This shielding leads to narrow and well-defined absorption bands. The transitions responsible for these absorptions involve \(f\) orbitals.