The characteristic narrow absorption bands in the spectra of lanthanoid ions arise due to f-f transitions. Which of the following lanthanoid ions will NOT exhibit these absorption bands?

Step-by-step solution

The narrow absorption bands in lanthanoids are due to the excitation of electrons within the 4f subshell ( f-f transitions). For these transitions to occur, the ion must have a partially filled 4f subshell ( 4f¹ to 4f¹³ ). The electronic configurations of the given ions are: Eu ³⁺ ( Z = 63 ): [ Xe ] 4f⁶ Pr ³⁺ ( Z = 59 ): [ Xe ] 4f² Sm ³⁺ ( Z = 62 ): [ Xe ] 4f⁵ Lu ³⁺ ( Z = 71 ): [ Xe ] 4f¹⁴ Since Lu ³⁺ has a fully filled 4f subshell, it cannot undergo f-f transitions and therefore does not exhibit these characterist