Thermoluminescence excitation spectroscopy: A versatile technique to study persistent luminescence phosphors

A versatile new facility to study photoionization processes in impurity doped compounds is presented. In this new facility monochromatic light is coupled to a thermoluminescence reader, enabling a fully automated recording of glow curves as a function of photon excitation wavelength. It provides detailed information on the mechanism of trap filling preceding persistent luminescence. The technique is first demonstrated with a study on Lu2SiO5:Ce3+ and then applied to commercial modern day double lanthanide doped SrAl2O4:Eu2+,Dy3+, Sr4Al14O25:Eu2+,Dy3+, CaAl2O4:Eu2+,Nd3+; and to the classical ZnS:Cu+ persistent luminescence phosphors. The presented data provide new insight into the mechanism of persistent luminescence.