Two-photon excitation to configuration of in crystal by KrF excimer laser

The two-photon excitation to high-lying levels of Gd 3 + via the intermediate D J 6 levels in LiGdF 4 and GdF 3 crystals has been studied under pumping by 248 nm radiation from a KrF excimer laser. Luminescence in the UV (204 nm), orange (570–640 nm) and IR (720–810 nm) regions, which is due to G J 6 – S 7 / 2 8 , G J 6 – P J 6 and G J 6 – I J 6 transitions in Gd 3 + , respectively, has been observed from the LiGdF 4 crystal at room temperature. No radiative transitions from the 4 f 7 G J 6 levels of Gd 3 + have been detected from the GdF 3 crystal. It was assumed that at low temperatures the two- photon excitation of the LiGdF 4 crystal with a KrF laser could result in the observation of short-wavelength upconverted VUV luminescence at ∼ 127 nm due to 4 f 6 5 d – 4 f 7 S 7 / 2 8 transitions in Gd 3 + .