A new neutron-deficient isotope,235Am

The level scheme of theN=82 nucleus¹⁴⁵Eu has been extended toI=(55/2) andE _x =11.2 MeV in an experiment with the Tessa Compton-suppressed Ge detector array using the¹²⁷I(²²Ne,4n) reaction. Most of the complicated and irregular level scheme of¹⁴⁵Eu can be interpreted as proton multi-quasiparticle states in comparison to the ₆₄ ¹⁴⁶ Gd₈₂ core nucleus but also excitations across the neutronN=82 core have been observed.     

High-spin levels in 63 145 Eu82

The level scheme of the N=82 nucleus ¹⁴⁵Eu has been extended to I=(55/2) and E_x=11.2 MeV in an experiment with the Tessa Compton-suppressed Ge detector array using the ¹²⁷I(²²Ne,4n) reaction. Most of the complicated and irregular level scheme of ¹⁴⁵Eu can be interpreted as proton multi-quasiparticle states in comparison to the ₆₄ ¹⁴⁶ Gd₈₂ core nucleus but also excitations across the neutron N=82 core have been observed.     

Magnetic dipole moments of the145–149Eu ground states

Nuclear orientation measurements at low temperatures have been carried out on radioactive isotopes of^145–149Eu in Fe and of^147,149Eu in Gd. The initial-state orientation coefficients determined from the measured gamma-ray anisotropies yield the magnetic dipole moments of the europium nuclei with A=145, 146, 147, 148 and 149 to be 3.2(5), 1.7(3), 3.1(4), 2.1(3) and 2.5(5), Μ_N, respectively. The values obtained for odd-A nuclei follow the systematics of the 5/2⁺ state magnetic moments of the nuclei in this region and are close to the values given by the single-particle model.     

Cross sections and γ-rays from multiple neutron capture in151Eu

Primary capture gamma rays following multiple neutron capture in¹⁵¹Eu have been measured as a function of the irradiation time. Neutron capture cross sections of the¹⁵²Eu 3^? groundstate and of the¹⁵²Eu 0^? isomer (T _1/2=9.3h) were determined. These cross sections are relevant for the interpretation of inelastic scattering of neutrons at isomeric states with energy gain (neutron acceleration). The level scheme of¹⁵³Eu has been extended. Neutron binding energies of¹⁵²Eu,¹⁵³Eu,¹⁵³Gd and¹⁵⁴Gd are given.     

Analysis on fluorescence of dual excitable Eu(TTA)3DPBT in toluene solution and PMMA

Photoluminescence of Eu(TTA)₃DPBT (TTA=thenoyltrifluoro-acetonate DPBT=2-(N,N-diethylanilin-4-yl)-4,6-bis(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine) in toluene and PMMA thin film are measured with excitation at 350 and 404 nm, respectively, and analyzed using Judd-Ofelt theory. Under excitation at 350 nm, it is found that Eu(TTA)₃DPBT in toluene has a larger Ω₂ value (14.33×10⁻²⁰ cm²) than that (12.70×10⁻²⁰ cm²) of Eu(TTA)₃Phen (Phen=1,10-phenanthroline) in the same solvent, and has a smaller Ω₂ value (12.70×10⁻²⁰ cm²) in PMMA than that (Ω₂=14.09×10⁻²⁰ cm²) of Eu(TTA)₃Phen in PMMA. At the same time, it can be seen that under excitation at 350 nm Ω₂ value of Eu(TTA)₃DPBT in toluene is larger than that in PMMA. Excited by 404 nm, Ω₂ of Eu(TTA)₃DPBT obtained in toluene and in PMMA are the same as that excited at 350 nm. The transition probability (A), emission cross-section (σ) and the fluorescence branching ratio (β) are also evaluated. The lifetime of ⁵D₀ metastable state is measured on 350 and 404 nm excitation, respectively. For the former situation, it is 455 μs in toluene and 640 μs in PMMA, for the latter it is 460 μs in toluene and 664 μs in PMMA. By comparing absorptions with excitations, it can be found that DPBT is more efficient than TTA as an energy donor. Phosphorescence spectra are also measured to estimate the lowest triplet level and analyze the energy transfer for DPBT and TTA, from which it is found that the energy transfer from TTA to DPBT occurs in the luminescent process.     

Structural,optical and electrical properties of europium picrate tetraethylene glycol complex as emissive material for OLED

A new europium complex [Eu(Pic)₂(H₂O)(EO4)](Pic)·0.75H₂O was synthesized and used as the emission material for the single layer device structure of ITO/EO4–Eu–Pic/Al, using a spin-coating technique. Study on the optical properties of the [Eu(Pic)₂(H₂O)(EO4)](Pic)·0.75H₂O complex where EO4=tetraethylene glycol and Pic=picrate anion, had to be undertaken before being applicable to the study of an organic light emitting diode (OLED). The electrical property of an OLED using current–voltage (I–V) measurement was also studied. In complex, the Eu(III) ion was coordinated with the EO4 ligand as a pentadentate mode, one water molecule, and with two Pic anions as bidentate and monodentate modes, forming a nine-coordination number. The photoluminescence (PL) spectra of the crystalline complex in the solid state and its thin film showed a hypersensitive peak at 613.5–614.9 nm that assigned to the ⁵D₀→⁷F₂ transition. A narrow band emission from the thin film EO4–Eu–Pic was obtained. The typical semiconductor I–V curve of device ITO/EO4–Eu–Pic/Al showed the threshold and turn on voltages at 1.08 and 4.6 V, respectively. The energy transfer process from the ligand to the Eu(III) ion was discussed by investigating the excitation and PL characteristics. Effect of the picrate anion on the device performance was also studied.     

Spin assignments from the 142Nd(7Li, 6He)143Pm and 144Sm(7Li, 6He)145Eu reactions at 52 MeV

Angular distributions have been measured for transitions to low-lying states in ¹⁴³Pm and ¹⁴⁵Eu populated by the ¹⁴²Nd(⁷Li, ⁶He)¹⁴³ and the ¹⁴⁴Sm(⁷Li, ⁶He)¹⁴⁵Eu reactions at $\text{E(}{}^7\text{Li}\text{) = 52}$ MeV. Elastic scattering of ⁷Li at 52 MeV on ¹⁴²Nd and ¹⁴⁴Sm, and ⁶Li at 46 MeV on ¹⁴²Nd and at 45 MeV on ¹⁴⁴Sm, were measured. Optical-model parameters extracted from fits to the scattering data were used in a finite-range DWBA analysis of the angular distributions for levels below 1.40 MeV excitation energy in ¹⁴³Pm and 1.84 MeV in ¹⁴⁵Eu. The reaction cross sections forward of 6° c.m. allow unambiguous distinction to be made between 2d_{$\text{5}\text{2}$} and 2d_{$\text{3}\text{2}$} final states. Final-state spins have been assigned to d-states in ¹⁴³Pm at 1.40 MeV($\text{3}\text{2}$⁺)and in ¹⁴⁵Eu at 1.042 MeV ($\text{3}\text{2}$⁺). Existing assignments to other levels in both residual nuclei have been confirmed.     

Energy transfer study of the formation, composition, and size of nanostructures of metal ion complexes in aqueous solutions

We studied the luminescence intensity (I _lum) of the ions Eu(III) and Sm(III) in relation to the concentrations of ions Ln(III) and Al(III) in water at pH 7 at an excess of such beta-diketones as p-methoxybenzoyltrifluoroacetone (MBTA), dibenzoylmethane (DBM), and tenoyltrifluoroacetone (TTA) and in the presence of 1,10-phenanthroline (phen) used as a synergistic agent. Both the enhancement of I _lum (Eu(III)) upon addition of Gd(III) (co-luminescence) and the effect of the third ion are found to depend on the order of addition of the ions to the solution and, therefore, on the sequence of formation of nanostructures of complexes of these ions in the solution, in which the transfer of the triplet energy of the organic part of complexes takes place, leading to an enhancement in I _lum (Eu(III)). The intensity I _lum (Eu(III)) is shown to increase equally rapidly upon addition of either Gd(III) or Al(III) to solutions with DBM + phen. In solutions of all the three beta-diketones studied, the Eu(III) ions incorporate better into nanostructures of triply charged ions whose radius is similar to or smaller than the radius of the Eu(III) ions. Our study of the effect that the replacement of H₂O with D₂O exerts of I _lum of 5 × 10^?8 M Eu(III) at different concentrations of ligands shows that, at [Ln(III)] < [OH^?] and at a concentration of beta-diketones smaller than 3 × 10^?5 M, the deuteration affects I _lum(Eu(III)) and, therefore, the first coordination sphere of Eu(III) contains OH groups. It is shown that, in aqueous solutions with 3 × 10^?5 M TTA + 10^?5 M phen, the increase in I _lum(Eu(III)) caused by the introduction of Gd(III) ions results from two processes occurring in the nanostructures of these complexes: the energy transfer from Gd(III) complexes to Eu(III) complexes and the increase of I _lum of Eu(III) itself under the conditions in the solution where the total concentration [Ln] ? [OH^?] and both the photochemical deactivation of Eu(III) and the exchange of its excitation energy for vibrations of the OH groups are suppressed. The reliability of the size estimation of nanostructures of metal complexes is discussed in terms of the effect of these nanostructures on I _lum of chelates of Eu(III).     

Excited states in124Xe

The isomer shift in the optical transition Eu II 4f⁷(⁸S ₇ ^2/o )⁶p_3/2 ^(7/2,3/2)4?4f⁷ (⁸S ₇ ^2/o )5d⁹D ₄ ^o , λ=6O4.95 nm, has been measured between the isotope^152gEu(3^?) and its isomer^152mEu(0^?). From the valuev(^152gEu)–v(^152mEu)=736(10) MHz the deformation parameter of^152mEu has been estimated to be^152mβ?+0.25. This value is smaller than^152gβ as obtained from isotope shift measurements and the spectroscopic quadrupole moment. The influence of the shape difference on the decay of^152mEu is discussed.     

Hypersensitivity in the Luminescence and 4f?C4f Absorption Properties of Mono- and Dinuclear EuIII and ErIII Complexes Based on Fluorinated ??-Diketone and Diimine/ Bis-Diimine Ligands

The results of our investigation on the sensitized luminescence properties of three Eu(III) ??-diketonate complexes of the form [Eu₂(fod)₆(??-bpm)], [Eu(fod)₃(phen)] and [Eu(fod)₃(bpy)] and 4f?C4f absorption properties of their Er(III) analogues ( fod = anion of 6,6,7,7,8,8,8- heptafluoro-2,2-dimethyl-3,5-octanedione, bpm = 2,2??-bipyrimidine, phen = 1,10-phenanthroline and bpy = 2,2??-bipyridyl) in a series of non-aqueous solvents are presented. The Eu(III) complexes are highly luminescent and their luminescence properties (intensity and band shape) are sensitive to the changes in the inner coordination sphere of the Eu(III) ion. The luminescence intensity of the mononuclear complexes in pyridine is drastically decreased. The coordination structure of the complexes in pyridine is transformed into a more symmetrical one which results into a slow radiative rate of the emission from the complexes. The ancillary ligands, phen and bpy are found better co-sensitizers as compared to the bpm to sensitize Eu(III)-luminescence. The 4f?C4f absorption properties (oscillator strength and band shape) of the Er(III) complexes demonstrate that ⁴G_11/2 ?? ⁴I_11/2 and ²H_11/2 ?? ⁴I_15/2 hypersensitive transitions of Er(III) are very sensitive in some coordinating solvents which reflects complex?Csolvent interaction in solution. The hypersensitive transitions of [Er(fod)₃(phen)] remain unaffected in any of the solvents and this complex retains its bulk composition in solution. The erbium complexes as well as the Er(fod)₃ chelate are invaded by DMSO. This solvent enters the inner coordination sphere by replacing heterocyclic ligand and the complexes acquire similar structure [Er(fod)₃(DMSO)₂] in this solvent. The results reveal that the luminescence and absorption properties of lanthanide complexes in solution can be controlled by tuning the coordination structure through ancillary ligands and donor solvents. This work shall prove useful in designing new biological applications with such probes.     

Itinerant and local magnetism,superconductivity and mixed valency phenomena in RM2Si2, (R = rare earth,M = Rh,Ru)°

X-Ray, magnetization and Mossbauer (¹⁵¹Eu, ¹⁵⁵Gd, ¹⁶¹Dy and dilute ⁵⁷Fe) studies of RM₂Si₂ reveal that when R is a magnetic ion the compounds order antiferromagnetically. For M = Rh a second antiferromagnetic phase transition is observed, corresponding to Rh itinerant electron magnetic ordering. In EuRh₂Si₂ the Eu ion is predominantly divalent with a mixed valent component. In EuRu₂Si₂ the Eu is predominantly trivalent. LaRu₂Si₂ and LuRu₂Si₂ display enhanced electron paramagnetism and become superconducting at 3.5 K and 2.4 K respectively. LaRh₂Si₂, YRh₂Si₂ and LuRh₂Si₂ display an itinerant electron magnetic phase transition, T_M (LaRh₂Si₂) = 7 K, and at lower temperatures a superconducting phase transition, T_c(LaRh₂Si₂) = 3.8 K. There is evidence that in the superconducting phase the itinerant magnetic order survives.     

Synthesis,crystal structure,and luminescence properties of CaY2Ge3O10:Ln3+, Ln = Eu,Tb

The crystal structure and luminescence properties of CaY₂Ge₃O₁₀:Ln³⁺ (Ln = Eu, Tb) germanates synthesized via a conventional solid-state reaction and an ethylenediaminetetraacetic acid complexing process are studied. The CaY_{2 ? x} Ln _x Ge₃O₁₀ (Ln = Eu, Tb; x = 0–1.0, 2.0; Δx = 0.1) solid solutions have a monoclinic structure (space group P2₁/c, Z = 4), in which dopant ions occupy three nonequivalent noncentrosymmetric sites with different Ca²⁺/Ln³⁺ ratios. The effect of the synthesis methods, dopant concentrations, and excitation wavelengths on the luminescence properties of the compounds obtained is determined.     

A 45 ns 8+ isomer in the doubly odd150Eu nucleus

In the doubly odd ₆₃ ¹⁵⁰ Eu⁸⁷ nucleus a 45 ns 8⁺ isomer at 589 keV excitation has been identified through (p, 3n) in beamγ ande ^? measurements. The low lying negative parity levels populated in its decay show great similarity to analogous states in the lighter odd-odd Eu neighbours suggesting a spherical shape for¹⁵⁰Eu. A spherical shape is also proposed for the isomer which is assigned as (πh _11/2 vf ₇ ^2/?3 )8⁺ state analogous to the 9⁺ isomers known in¹⁴⁸Eu and¹⁴⁶Eu. The spin change is attributed to the crossing of the half-filledf _7/2 neutron shell atN=86.     

Die Isotopieverschiebung von151Eu,152Eu,153Eu,154Eu und die Kernmomente der radioaktiven Isotope152Eu und154Eu

The isotope shift of the stable¹⁵¹Eu,¹⁵³Eu, and the radioactive¹⁵²Eu,¹⁵⁴Eu isotopes and the hyperfine splitting of the¹⁵²Eu isotope was investigated using a digital recording Fabry-Perot-spectrometer. From isotope shift measurements on the line λ 5 765 Å (4f ⁷ 6s 6p z⁶P_7/2-4f ⁷ 6s² a⁸S_7/2) the relative isotope shift was derived:¹⁵¹Eu:0;¹⁵²Eu: 0.923(8);¹⁵³Eu: 1;¹⁵⁴Eu: 1.197(8). The results show that there is a strong increase in the change of the mean square nuclear charge radius δ〈r²〉 when only one neutron is added to the 88 neutrons of the¹⁵¹Eu nucleus, whereas the change of δ〈r²〉 between¹⁵²Eu and¹⁵³Eu is of the same order of magnitude as that between¹⁵³Eu and¹⁵⁴Eu. From the hyperfine splitting of the radioactive isotope¹⁵²Eu in the line δ 6865 Å (4f ⁷ 6s 6p z ¹⁰ P _9/2-4f ⁷ 6s² a⁸S_7/2) the sign of the magnetic dipole moment μ_I(¹⁵²Eu) was found to be negative, and with this result and earlier experimental data the signs of the nuclear quadrupole momentsQ(¹⁵²Eu) andQ (¹⁵⁴Eu) could be determined to be positive.     

Electric field gradients at 151Eu sites in GaN

The electric field gradients at Eu sites in GaN have been investigated in conversion electron Mössbauer spectroscopy (CEMS) in which ¹⁵¹Eu probe ions were implanted into an undoped GaN layer grown on a sapphire substrate. The sample was implanted with 120 keV ¹⁵¹Eu ions to a fluence of 1 × 10¹⁵, and annealed at 1,200 K. CEMS spectra of the ¹⁵¹Eu 21.6 keV transition were collected, of the GaN sample as well as of a Si sample implanted with overlapping profiles of ¹⁵¹Eu and O. The GaN spectra were fitted with two symmetric doublets, D1 and D2, with isomer shifts and quadrupole splittings of δ?=??0.27 mm/s (relative to Eu₂O₃), ΔE _Q?= 0.85 (3) mm/s; and δ?=?? 0.22 mm/s, ΔE _Q?= 2.90 (5) mm/s, respectively. D1 is attributed to Eu at substitutional Ga lattice sites; D2 to Eu at or near substitutional sites but with extensive lattice damage. The splittings of D1 and D2 correspond to quadrupole coupling frequency of 15 (2) and 50 (4) MHz, consistent with measurements of ⁶⁹Ga, ⁷¹Ga and ¹¹¹In in GaN.     

151Eu Mössbauer Spectroscopy in La0.38Eu0.29Ca0.33MnO3

Electrical conductivity with and without magnetic field, d.c. magnetization and ¹⁵¹Eu Mössbauer studies were carried out in La_0.38Eu_0.29Ca_0.33MnO₃ perovskite manganite system. An insulating ground state is found throughout the temperature range with charge ordered (CO) state emerging at T _CO ～ 140 K, where as an external magnetic field of 6 T induces metal-insulator transition at ～120 K. D.C. magnetization measurements show the antiferromagnetic (AFM) transition occurring at T _N ≈ 48 K. The temperature dependent ¹⁵¹Eu Mössbauer measurements showed that the substituted Eu replaces La³⁺ in the 3+ charge state and a small magnetic moment gets induced at the Eu nucleus at low temperatures. The anomalous variation of the f- factor with temperature occurring around T _N and T _CO corroborates the occurrence of antiferromagnetic (AFM) and charge ordering (CO) transition, respectively.     

Nuclear levels in152Eu

The transitional nucleus¹⁵²Eu has been studied using the (n, e), (n, γ), (n _res,γ), (n, γγ), (d, p), (d, t) and (p, d) reactions. The experiments have been performed at nine different laboratories. A model independent level scheme was established including 95 levels below 510 keV and nearly 900 transitions by combination of low energy transitions and reaction data. More than 20 additional levels result from gamma rays and/or charged particle reactions. The level scheme is interpreted in terms of the Nilsson model indicating that¹⁵²Eu is a deformed nucleus. Seven rotational bands and Nilsson configurations are established. An additional 27 rotational bands are tentatively or speculatively assugned. Gallagher-Moszkowski splittings are discussed. The neutron binding energy was determined as 6305.2±0.5 keV. The energy of the 9.3 h 0^? isomer is 45.599 keV. The lifetimes of four levels were measured. Nuclear Reactions¹⁵¹Eu(n,γ),E _n =thermal and resonance; measuredE _γ ,I _γ ,E _c.e.,I _c.e.,γγ Coinc.,γγΔt coinc.;¹⁵¹Eu(d, p),E=12MeV and 14MeV;¹⁵³Eu(d, t),E=12MeV;¹⁵³Eu(p, d),E =18MeV; deduced level scheme of¹⁵²Eu,J, π, T _1/2,cc, Nilsson configurations. Magnetic electron spectrometer, curved crystal spectrometer, Ge(Li) and Si(Li) detectors, magnetic spectrographs. Enriched targets.     

On the valence stability of Eu in the laves phase compounds Eu1-xPtxPt2 under high-pressure

High-pressure Mössbauer studies of the ¹⁵¹Eu resonance in Eu_1-xPt_xPt₂ (x = 0;0.143;0.25) have been performed between 4.2 and 300 K. A linear decrease in the magnitude of the interconfiguration excitation energy E_exc on the Eu²⁺-site with decreasing lattice constant was found (?|E_exc|/?lnV = 1.6 x 10⁴K). The isomer shift for EuPt₃ at 70 kbar and 4.2 K shows that the Eu atoms on the Eu²⁺-site are no longer pure divalent but have ? 5% admixture of the Eu³⁺ cofiguration.     

Systematics of EPR spectra of GD3+ in some isostructural rare-earth trisulphate octahydrate hosts

X-band data on Gd³⁺ ions doping some isostructural single crystals of rare-earth trisulphate octahydrate [R₂(SO₄)₃·8H₂O] single crystals (RSH) have been obtained at room temperature for the hosts characterized by R = Pr, Nd, Sm, Eu, Yb and Y, and at liquid nitrogen and liquid helium temperatures for the hosts characterized by R = Pr, Sm, Eu and Y. The data are analyzed using a rigorous least-squares fitting procedure in which all resonant line positions obtained for various orientations of the external magnetic field are fitted simultaneously to the same spin Hamiltonian parameters. The intensities of the lines obtained at liquid helium temperatures indicate the absolute sign of the parameter b₂⁰ to be negative for R = Pr, Eu and Y, whereas for the Sm host the sign of b₂⁰ is found to be positive. While the parameter b₂⁰ does not exhibit a clear cut linear dependence upon the host ion radius, the parameter b₂⁰ is found to behave approximately linearly as a function of the host-ion radius. On the other hand, the zero-field splitting is found to be a linear function of the host ion radius at all three temperatures—room, liquid nitrogen and liquid helium.A comparison is presented of the systematics of the EPR spectra for the RSH hosts with those for some other isostructural rare-earth hosts.     

Investigation of Europium (III)-Rutin Complex in Water-Ethanolic Solution

Abstract

The composition and the stability constant of Eu(III)-rutin complex were determined by suitable spectrophotometric methods and pH-metric measurements. The formation of a (Eu(C₂₇H₂₆O₁₆H₃)₂)⁺ complex whose concentration stability constant β₂ ranged from 10.59 at pH=5.0 to 7.21 at pH=8.0, was established. Spectrophotometric determination of Eu(III) by means of the reaction of complex formation with rutin, was investigated. It was found that Eu(III) can be determined in the range from 5×10^?6 to 7.5×10^?5M. All investigations were carried out with 70% ethanolic solutions at room temperature (20°C), whereas spectrophotometric investigations were performed in the presence of a buffer, at constant pH values and ionic strength (0.015). The determination of the complex composition was done at pH=5.6, and that of Eu(III) at pH=6.3.