Low-temperature high-resolution VUV spectroscopy of Ce3+ doped LiYF4, LiLuF4 and LuF3 crystals

For LiYF4:Ce3+, LiLuF4:Ce3+ and LuF3:Ce3+ crystals UV/visible emission and time-resolved VUV/UV excitation spectra were recorded at liquid helium temperature with spectral resolution of 0.1 nm for excitation spectra and better than 0.3 nm for emission spectra. Well resolved fine structures due to zero-phonon lines were clearly observed in both excitation and emission spectra for LiYF4:Ce3+ and LiLuF4:Ce3+. For LuF3:Ce3+ crystal no fine structure was detected in the spectra even at the highest spectral resolution. Under the host excitation, the fine structure for high-energy emission band of Ce3+ (5d–2F5/2) in LiLuF4:Ce3+ becomes well pronounced because of weaker reabsorption effect, as compared to Ce3+ 4f–5d absorption, due to small penetration depth for exciting radiation. As a result the crystal-field splitting for 2F7/2 and 2F5/2 levels of Ce3+ in LiLuF4 crystal was measured. First observation of zero-phonon lines at ∼81,550 and ∼82,900 cm−1 as well as vibronic side bands due to interconfigurational 4f14–4f135d transitions in Lu3+ is reported for excitation spectrum of LiLuF4:Ce3+.