Abstract In lanthanides transitions involve only a redistribution of electrons within the 4f-orbitals (f↔f transition) are orbitally forbidden by the selection rule. Crystal field effects in lanthanides are virtually insignificant due to 4f-electrons are well shielded from external charge by 5s2 and 5p6 sub-shells. Their (f↔f transition) absorption bands are very sharp. Their optical spectra are virtually independent of environment they show similar spectra in gas/solution/solid (sharp lines like typical gas atom spectra). Analysis of the UV-Visible spectra for rare earth ions in aqueous solutions are complex.
Keywords Lanthanide, sharp-spectra, transition