Spin-Allowed and Spin-Forbidden fd Emission from Er3+ and LiYF4
ABSTRACT Luminescence measurements in the vacuum ultraviolet of 4f11-->4f10 5d transitions on Er3+ in LiYF4 have shown the presence of a weak fd band. The weakness of the band is explained by the spin-forbidden character of transitions from the ground state to this fd state, which is at lower energy than the spin-allowed fd bands. Upon excitation in the spin-allowed fd bands, both fast spin-allowed fd emission (tau=5 ns) and slow spin-forbidden fd emission (tau>2 mus) are observed. These results can be understood with a configurational coordinate diagram analogous to the Jablonski diagrams that are used to explain the fluorescence and phosphorescence from organic molecules.
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- "Surprisingly, the dominant VUV emissions in these two closely related materials, shown in Figs. 1 and 2, are different. The emission of BaF 2 :Er, peaking at 163.5 nm, is slow, as reported earlier  , and similar to VUV emissions from other Er-activated fluorides . The emission of (Ba,La)F 2 :Er, peaking at 162.5 nm is, unexpectedly, relatively fast (35 ns at room temperature and 45 ns at 10 K). "
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ABSTRACT: The laser induced fluorescence spectrum of Tb3+ ions in LiLuF4 single crystals, pumped by a fluorine pulsed discharge molecular laser at 157.6 nm, was obtained in the vacuum ultraviolet (VUV) and ultraviolet (UV) regions of the spectrum. The 4f75d→4f8 dipole allowed transitions originate from the Stark components and the edge of the levels of the 4f7()5d electronic configuration. The LIF spectra were interpreted on the basis of phonon trapping and phonon reabsorption within the levels of the 4f75d electronic configuration. The absorption spectrum of the crystal samples in the VUV was obtained as well. We observed eight transitions between the ground level 4f8() and the Stark components of the levels of the 4f7()5d electronic configuration and five transitions between the ground level 4f8() and the Stark components of the levels of the 4f7()5d electronic configuration. The edge of the levels of the 4f75d electronic configuration was found to be at 45.2×103±0.2×103 cm−1 and the band gap of the crystal host was 77.6×103±0.3×103 cm−1 wide.Optics Communications 11/1998; 156(s 1–3):101–111. DOI:10.1016/S0030-4018(98)00367-8 · 1.54 Impact Factor
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ABSTRACT: The laser-induced fluorescence spectrum (LIF) of LiLuF4:Ho3+ single crystals pumped by a molecular F-2 pulsed-discharge laser at 157.6 nm is obtained in the vacuum ultraviolet (VUV) and UV regions of the spectrum, The observed transitions originate from the levels and the edge of the 4f(9)5d electronic configuration, and they are assigned to the 4f(9)5d --> 4f(10) interconfigurational transitions. The LIF spectra for the dipole-allowed transitions can be explained provided that phonon trapping of the lattice vibrations is taking place within the Stark components of the 4f(9)5d electronic configuration. The absorption spectrum of the crystal samples in the VUV was obtained as well. We observed five main transitions between the ground level I-5(8) Of the 4f(10) electronic configuration and the Stark components of the levels of the 4f(9)5d electronic configuration in the spectral range between 125 and 150 nm, and we observed four main spin-forbidden transitions in the spectral range from 153 to 170 nm.Journal of the Optical Society of America B 04/1999; 16(4):625. DOI:10.1364/JOSAB.16.000625 · 1.81 Impact Factor