4f–5d absorption of gadolinium ions in sodium gadolinium tetrafluorides

Excitation spectra in the vacuum ultraviolet/ultraviolet (VUV/UV) spectral region (100–300 nm) have been investigated for luminescence of Gd3+ ions appearing at ∼310 nm in NaGdF4. It is found that at room temperature there appears an excitation band peaking at ∼160 nm, which is suited for the absorption of the VUV light generated from Xe discharge (150–200 nm). The origin of the excitation band is discussed in terms of the 4f–5d transitions of Gd3+ ions in NaGdF4.