Excitation and Spectral Dependence of the Rise and Decay Time Responses of Eu 2+ - and Dy 3+ -Doped Strontium Aluminates

In this paper, we study the phosphorescence rise and decay time responses of Eu2+- and Dy3+-doped strontium aluminates prepared by different methods after scanning them with a narrow spectral width (15 nm FWHM) light from a monochromator. The experiments performed show that the time responses essentially depend on the excitation duration as well as on the excitation and the emission wavelengths. It has been found that at the excitation wavelength of maximum efficiency λ′max, a ‘fast track’ rise and decay of the phosphorescence exists. We suggest that by studying the normalized switch on and switch off time responses, we can determine the relative share of slow phosphorescence afterglow with respect to fast and slow phosphorescence decay as well as the rate of luminescence rise and decay processes. The relation to the synthesis technology and to the contents of the samples is discussed.