Communication: X-ray excited optical luminescence from TbCl3 at the giant resonance of terbium

We have studied the optical recombination channels of TbCl(3) using x-ray excited optical luminescence at the N(4,5) absorption edge of Tb (giant resonance) in both the energy and time domain. The luminescence exhibits a relatively fast (5)D(3), and a slow (5)D(4) decay channel in the blue and green, respectively. The rather short lifetime of the (5)D(3) state indicates that the decay is mainly driven by Tb-Tb ion interaction via non-radiative energy transfer (cross-relaxation). At the giant resonance the X-ray Absorption Near Edge Structure (XANES) recorded using partial photoluminescence yield is inverted. In the pre-edge region the contrast of the spectral feature is significantly better in optical XANES than in total electron yield. Changes in the intensity of (5)D(3)-(7)F(5) (544 nm) and (5)D(4)-(7)F(6) (382 nm) optical transitions as the excitation energy is tuned across the giant resonance are also noted. The results provide detailed insight into the dynamics of the optical recombination channels and an alternative method to obtain high sensitivity, high energy resolution XANES at the giant resonance of light emitting rare-earth materials.