LUMINESCENCE OF PR3+-ACTIVATED THORIUM-OXIDE

The luminescence of Pr3+ is determined not only by the nature of the lattice in which the ion is incorporated but also by the calcination temeperature of the sample and by the excitation process: photoluminescence or cataluminescence, i.e. chemiluminescence specific of catalysis. For the two different excitation sources, it is assumed that the excitation occurs either in the 4f5d bands with photons of the wavelength of 275 nm or in the charge transfer band during the course of the catalytic reaction. The interpretation of the different relative intensities of the emission from the 1D2 and 3Po levels results upon the existence for the Pr3+ ions of at least two sites, the relative populations of which change according to the preparation mode. © 1979.