[Concentration dependence of luminescence under different excitation wavelength in Y2O2S:Sm3+ phosphor].

The concentration dependence of luminescence under different excitations in Y2O2S:Sm3+ phosphor has been studied. The optimum activator concentration was found to be a function of the number of excited activator ions as well as the excitation wavelength. The concentration dependence curve of Y2O2S:Sm3+ phosphor under 413 nm excitation was different from the curve obtained with 263 nm excitation. For excitation radiation having longer wavelength (413 nm), the concentration quenching of Y2O2S:Sm3+ phosphor occurred at about 2%, which is ten times the result with shorter wavelength (263 nm) excitation (-0.2%). Fitting the concentration dependence curve and the result shows that the cross-relaxation caused by the dipole-quadrupole interaction of neighboring Sm3+ ions results in the concentration quenching.