Thermal Quenching of Tb+3, Tm+3, Pr+3, and Dy+3 4fn Emitting States in La2 O2 S

Abstract
Thermal quenchings of +3 rare‐earth line emissions were measured for excitation into the 4fn emitting states. These quenchings differ from corresponding quenchings reported by Wickersheim and Buchanan for band‐gap excitation. For Tb+3, Tm+3, and possible Pr+3, the quenchings from the 4fn emitting states are attributed, as in the previously well‐established Eu+3 case, to thermally promoted crossovers to Franck‐Condon‐shifted states.