- P-ISSN 1225-0163
- E-ISSN 2288-8985
Energy transfer process between <TEX>$Tb^{3+}$</TEX> and <TEX>$Ce^{3+}$</TEX> has been studied in LaOCl host. The energy absorbed by <TEX>$Ce^{3+}$</TEX> transfers to <TEX>$Tb^{3+}$</TEX> which has levels emitting strong fluorescence. The probability of energy transfer depends strongly on the concentration or the distance of activator ions. While the energy transferred on <TEX>$Tb^{3+}$</TEX> emits from <TEX>$^5D_3$</TEX> level at low concentration of <TEX>$Ce^{3+}$</TEX>, the energy goes back to <TEX>$Ce^{3+}$</TEX>(Back Transfer) and then emits from low levels of <TEX>$Ce^{3+}$</TEX> and <TEX>$Tb^{3+}$</TEX> at the high concentration. The Back Transfer process has been identified by the experiment with varying the concentration of the activator, <TEX>$Ce^{3+}$</TEX>. The relaxation is more effective if <TEX>$Ce^{3+}$</TEX> intermediates than if not.