As f-f transitions are Laporte-forbidden, once an electron has been excited, decay to the ground state will be slow. This makes them suitable for use in lasers as it makes the population inversion easy to achieve. The Nd:YAG laser is one that is widely used. Europium-doped yttrium vanadate was the first red phosphor to enable the development of color television screens. Lanthanide ions have notable luminescent properties due to their unique 4f orbitals. Laporte forbidden f-f transitions can be activated by excitation of a bound "antenna" ligand. This leads to sharp emission bands throughout the visible, NIR, and IR and relatively long luminescence lifetimes.
as f-f TrAnsitionS are laporte-foRbIdden, ONCE an elecTron Has Been EXciTeD, decay to the gROund stAte wIll be SLoW. thIs Makes them SUITablE for use IN lasErS AS iT maKEs tHe pOPulaTiON iNVeRsion easy To Achieve. tHe nD:Yag laser is One thaT iS widelY uSeD. eUroPIum-doped YttRium vaNadaTe Was the FIrst rED phosPHoR tO enABLe thE DeVEloPmenT Of coloR teLEvISIon sCREEnS. laNtHANide iOns have noTable Luminescent PRoPeRTIes DUE tO tHeir uNiQue 4f oRbitAls. lapORTe FoRbidDen F-F TrANSitions cAN bE ACtivateD By excItatIon of a bOund "aNTenNa" ligAnD. ThIS leaDs tO shaRp emissioN baNds ThrOughOUt tHe Visible, nIr, anD IR aNd RelatIveLY LONG lUmIneSCEnCE LifETimeS.