Luminescence mechanism

A hole transport model 

For such materials, the first model is made in such SrAl2O4 Matsuzawa: Eu, Dy hole transport system model proposed. Based on this model, Matsuzawa that in Long Afterglow SrAl2O4: Eu, Dy in, Eu electron trapping centers, glow in the dark dye‍ Dy is the hole-trapping centers. When the material is excited by UV, Eu can capture electrons into Eu, resulting hole valence band are generated by capturing Dy Dy, after stoppage of the excitation, the relationship of thermal motion, the occurrence of the escape hole, and the above process through the opposite result of the process and characteristics of the light-emitting Eu schematic diagram shown in Figure 3. The model Eu and Dy in a variety of long-lasting co-doped materials have been widely interpreted as a mechanism of reference become a common interpretation Eu and Dy co-doped mechanism of long-lasting material. 

2 displacement coordinate model 

Displacement coordinate model was glow in the dark material‍ first Jianrong and Su Qiang et al. Figure 3 is a schematic diagram of the displacement coordinate model. A is the ground level of Eu2 +, B for its excited state level, C level of defect levels. C may be incorporated into the impurity ions may be some defects caused by defects in the matrix of the levels. Su Qiang and others that C can play the role of electron capture. Under the effect of the external light source, excitation by electron transition from the ground state to an excited state (a), part of the electron-emitting transition back to a lower energy state (2). Another part of the electronic relaxation processes by energy stored in the defect and C in (3). When the electron absorbs energy defect level, re-excited by return to excited states, the transition to the ground state and emit light. The duration and the number of electrons stored in the defect levels, and absorb energy (heat) on the twilight, the more the number glow in the dark stones‍ of electrons in the defect level, the longer the afterglow time, energy absorption and more, resulting in continuous light.