Luminescence of LuCl $_3$ Doped With Pr $^{3+}$

The optical properties of Pr³⁺ activated LuCl₃ under intra-ionic 4f² rarr 4f¹ 5d¹ and band gap (lambda_ex = 193 nm; X-ray) excitations has been evaluated. The luminescence of LuCl₃ :Pr³⁺ is found to be strongly dependent on the excitation energy: for energies less than the absorption edge of the host, the luminescence of LuCl₃: Pr³⁺ is dominated by the 4f¹ 5d¹ rarr 4f² interconfigurational optical transitions. When luminescence is excited by photons with energies corresponding to the absorption edge or the band gap of the host, the emission spectrum is dominated by the intraconfigurational 4f² rarr 4f² optical transitions, which emanate from the Pr³⁺ 3P_J states. The luminescence efficiency of the inter- and intraconfigurational optical transitions is high at room temperature. A model to account for the dependence of the emission behavior of Pr³⁺ ion on the excitation energy is presented.