Luminescence of Pr-doped LiCaAlF6 and LiSrAlF6 crystals

The spectral and kinetic parameters of LiCaAlF₆:Pr and LiSrAlF₆:Pr single crystals are studied at LHeT and room temperature (RT). Photon cascade emission (PCE), i.e., ¹S₀→¹I₆ and ³P₀→³H_j, ³F_j transitions after Pr³⁺ excitation via 4f²→4f 5d absorption results in the conversion of the vacuum ultraviolet photon to two visible photons. The excitation and photoemission spectra as well as decay times have been measured and compared with those for CaF₂:Pr and SrF₂:Pr crystals. X-ray luminescence was measured to study the emission origin from both ¹S₀ and ³P₀ states of Pr³⁺. An intense phosphorescence of LiSrAlF₆:Pr was observed in the visible range after X-irradiation at RT, contrary to LiCaAlF₆:Pr.