Luminescence Spectra Of Eu Research Articles

Pressure-induced phase transition in YVO 4:Eu 3+: A luminescence study at high pressure

The pressure dependence of the emission from the Eu 3+ ion in YVO 4:Eu 3+ has been investigated to 14 GPa, using a diamond anvil cell. Abrupt changes in the luminescence spectra of Eu 3+ ion at 7 GPa, which, after removal of pressure, did not reverse, indicated that a pressure-induced, irreversible phase transition had occurred. The luminescence spectra from the high pressure phase showed the characteristics of a distorted D 2d symmetry, which can be explained by considering only the first coordination sphere oxygens about the Eu 3+ ion in an S 4 symmetry site. The change in the energy separation between the 5 D 0 and 7 F 0 levels from the low pressure phase to the high pressure phase is discussed. A decrease of the effective charge on the oxygen atoms in the high pressure phase occurs and is correlated with a charge transfer mechanism that arises because of the phase transition.

Spectroscopy of trivalent europium in gel-derived silica glasses

Abstract Luminescence spectra of Eu3+ in sol-gel-derived silica (SiO2) samples are reported and discussed as a function Eu3+ concentration and of heating. Lifetimes, linewidths and Stark splittings of the transitions are used for monitoring structure evolutions of the gel network; the data in the interval 25–250°C allow us to describe the general behaviour of the system during SiO, gel→txerogel transition.

High pressure effect on the luminescence spectra of Eu 3+ in stoichiometric host microcrystals

Na 5Eu(MoO 4) 4 and Na 5Eu(WO 4) 4 are two good stoichiometric host luminescent materials having high concentrations of Eu 3+. The effect of hydrostatic high pressure on their luminescent spectra has been investigated. The emission spectra of Na 5Eu(MoO 4) 4 and Na 5Eu(WO 4) 4 were measured at pressures up to 40 kbar and 80 kbar, respectively, using a high pressure microspectroscopic system in conjunction with a gasketed diamond anvil cell at room temperature. The red shift of the emission lines and energy levels under high pressure have been measured. According to crystal field theory, the pressure dependence of the crystal field parameters have been deduced from the experimental data.

High pressure phase transformation of ScOC1; X-ray and europium luminescence studies

A phase transformation has been induced in ScOC1 by application of high pressure and temperature (P = 25 kbar, T = 700 C). The structure changes from orthorhombic to hexagonal. No phase transformation could be evidenced in InOC1 submitted to the same conditions. Luminescence spectra of Eu 3+ in orthorhombic ScOC1 and InOC1 are described.

Application of luminescence and absorption spectroscopy and the x-ray method to the study of Ln 3+ ions interaction with aminoacids

Lanthanide ions have found increasing use as metal ion probes for spectroscopically inert Ca(II), and substitution of Ln(II) for Ca(II) enables the performance of absorption, luminescence and magnetic resonance studies on systems of biological interest. In peptide and protein complexes, the Ca(II) ion is normally bound by aspartate and glutamate residues so it is crucial to the full understanding of Ln(III) binding by these materials. In our previous papers we have examined the interaction of lanthanide ions with L-asparagine, L-glutamine, L-aspartic and L-glutamic acid in aqueous solutions. We have suggested the appearance of the dimeric forms in the latter case [1–4]. Now we report the results of our spectroscopic studies of the crystals of the Nd, Ho and Eu compounds with glycine and L-glutamic acid in solid state and of the X-ray investigations of the [Nd(gly) 3][ClO 4] 3·5H 2O crystal. Several lanthanide ion complexes with glycine and L-glutamic acid were synthesized and yield in the form of monocrystals. Absorption spectra of the crystals were measured on a Cary 14 spectrophotometer at room temperature and 5 K. Luminescence spectra of Eu(III) and Nd(III) compounds were recorded at the same temperature. E 1 and E 2 selective excitation energies of the Nd(III) ion level revealed that the Nd(III) ion could appear in two different symmetry positions in the complexes with glutamic acid. From the measured absorption spectra the oscillator strengths of f–f transitions were estimated. The relation between f–f transition intensity and position of the crystallographic axis of crystals has been stated. The f–f transitions were analysed on the basis of the Judd theory taking the dependence of intensity on the crystallographic axis position into account. Intensity analysis of f–f transitions revealed quite a considerable difference in the intensity distribution of bands, especially for hypersensitive transitions. Drastic differences in Judd parameters have been found (Table I). t001 The τλ Parameters Values. Compound τ 2 × 10 9 τ 4 × 10 9 τ 6 × 10 9 [Nd(Gly) 3][ClO 4 3·5H 2O a 3.65 ± 0.85 5.48 ± 0.78 11.49 ± 1.10 b 3.25 ± 0.68 5.67 ± 0.63 10.70 ± 0.88 c 1.83 ± 0.93 6.17 ± 0.86 10.40 ± 1.20 a (mean) 2.83 ± 0.76 5.92 ± 0.71 10.80 ± 0.99 [Nd(Glu)][ClO 4] 2·7H 2O 4.72 ± 0.73 5.44 ± 0.68 12.44 ± 0.95 The crystal structure data determined by us for [Nd(Gly) 3][ClO 4] 3·5H 2O compound with space group P1, Z = 4, symmetry for Nd +3; I-1 and C.N. = 9 (Fig. 1) confirm our suggestion that in lanthanide ▪ ion complexes with aminoacids dimeric and polymeric structures may be observed.

Determination of europium(III) in rare earth oxide sulfide phosphors by lifetime measurements

The lifetimes for three transitions, 5D 2 → 7F 0, 5D 1 → 7F 1 and 5D 0 → 7F 2, in the luminescence spectra of Eu x 3+:Y 2-xO 2S (x=0.001–0.12) are reported. The relation between the lifetime of the transition 5D 0 → 7F 2 and the europium concentration is sufficiently linear in the concentration range 2–10% for the lifetime method to be used for the determination of europium in rare earth oxide sulfides. The accuracy of the method is compared with that of the linear intensity ratio method.

A luminescent probe study of the details of complexing with macromolecule ligands

1. A study has been made of the luminescence spectra of Eu3+ complexes with various macromolecular ligands, comparison being made with the spectra for the low-molecular-weight analogs. 2. It has been shown that the method of luminescent probes can be used to obtain information concerning the details of complex formation with macromolecular ligands.

Ternary Lanthanide Complexes of the Type M(Hsal)3(TPX → O)2 and a Fluorescence Spectral Study of the Eu(III) Analogue

Ternary lanthanide complexes of the general formula M(Hsal)3 (TPX→O)2 , where M = lanthanide (III) ion, Hsal=salicylate ion =C6H4(OH)COO- and X = P or As have been isolated as solids from the benzene phase during liquid-liquid extraction studies of M(Hsal)3 complexes with benzene solutions of TPX→O. The coordinated nature of the TPX→O ligands has been established from the observed shifts of the X → O frequency in the infrared. A lowering of the 1190 cm-1 P → O frequency where X = P , and an increase in the 885 cm-1 As → O frequency where X = As have been observed for the ternary complexes. The infrared spectra of the ternary complexes in general indicate the coordinated nature of the salicylate ions. The luminescence spectra of Eu(Hsal)3 (TPPO)2 and Eu(Hsal)3 (TPAsO)2 complexes have also been investigated at 77 °K. Beside the emission of the characteristic red europium fluorescence due to the excitation of the complexes with near UV light, emission of a blue molecular phosphorescence from the complexes has also been observed. The fluorescence intensities of the f → f transitions are, however, weak. This point has been discussed.

Spin-wave sideline in the luminescence spectra of Eu 3+ ion in KMnF 3

Spin-wave sidelines were observed in the luminescence spectra of Eu 3+ ion doped in antiferromagnetic KMnF 3 crystals.

Vibronic Structure in Luminescence Spectra of Rare Earth Ions In SrTiO3, BaTiO3 and Other Perovskites

In the luminescence spectra of Eu 3+ in SrTiO 3 , two kinds of vibronic structure, i.e. , rather sharp satellite lines (vibronic lines) and asymmetric bands (vibronic tails), were found to exist. The tails were observed also in the spectra of Tb 3+ and Pr 3+ in SrTiO 3 . The tail strongly appears associated only with transitions allowed by forccd electric dipole. A comparison of the luminescence spectra of Eu 3+ in SrTiO 3 and BaTiO 3 has suggested the existence of a correlation between the strength of vibronic structure and the site symmetry of rare earth ions. To investigate this, the luminescence spectra of Eu 3+ were studied in various perovskite type oxides in which the site symmetry of Eu 3+ varies from O h to very low symmetries. It has been clarified that the vibronic lines strongly appear when the site symmetry is O h or very close to it. However, the vibronic tail was observed only in SrTiO 3 . In order that the vibronic tail appears, some special properties of host material seem to be required.