Spectroscopy of Trivalent Praseodymium in Barium Yttrium Fluoride

Abstract

This work reports the results of an investigation of the spectroscopic properties of trivalent praseodymium (Pr³⁺) in barium yttrium fluoride (BaY₂F₈). Two doping concentrations were used: BaY₂F₈:Pr³⁺ (0.3%) and BaY₂F₈:Pr³⁺ (1%). Absorption spectra, taken at 77 and 300 K, allowed the placement of the energy levels of the 4f² electronic configuration of Pr³⁺. Luminescence spectra were obtained with transitions originating mainly in the metastable levels ³P₀, ¹D₂, and ³F₃. Time-resolved spectroscopy was used to clarify the assignment of several spectral lines.

The lifetimes of both ³P₀ and ¹D₂ were found to be essentially independent of concentration and temperature with values of 55 and ∼250 μs respectively, in the temperature range 77 to 500 K. In the same temperature range, the lifetime of the ³F₃ level was found to vary from 23 ms at 77 K to 5 ms at 500 K. The effects of temperature on the widths and positions of several spectral lines originating in the ³P₀ and ¹D₂ levels were studied. The mechanism of Raman scattering of phonons fitted the observed results with an effective Debye temperature of 500 K.