Revisiting the SrAl 2 O 4 :Eu 2+ ,Nd 3+ persistent phosphor

The SrAl 2 O 4 :Eu 2+ ,Nd 3+ persistent phosphor emits green (Eu 2+ ) and infrared (Nd 3+ ) persistent luminescence (PersL) and the PersL excitation (Ex.) spectra of Eu 2+ and Nd 3+ are different from their respective photoluminescence (PL) excitation spectra.