Luminescence and excitation spectra of Nd3+ in Cs2NaGdCl6 : NdCl 3–6

Abstract

The ⁴F_3/2, ⁴F_5/2 and ⁴G_7/2 luminescence spectra of Nd³⁺ in the cubic host Cs₂NaGdCl₆ between 20 000–3600 cm^–1 and the ⁴F_3/2→⁴I_9/2 excitation spectra between 20 000–11 360 cm^–1 have been recorded between 300 and 10 K. The intensity in each transition region is assigned to magnetic-dipole-allowed zero-phonon lines and electric-dipole-allowed vibronic structure comprising NdCl^3–₆ moiety and lattice mode vibrations. 41 crystal-field levels of Nd³⁺ have been located from the vibronic sidebands and symmetry representations were assigned on the basis of energy level calculations and from comparisons of calculated and observed magnetic-dipole line strengths. The non-radiative decay rate of the (⁴G_7/2)Γ₇ level is ca. 250 times faster than that of (⁴F_3/2)Γ₈, and reasons for this are discussed.