Tensor polarizabilities of the 4f 7(8 S)5d6s 2 9 D 2,3,4,5,6 levels in Gd I

The optical pumping method with rf detection and the nonlinear level crossing technique were used in parallel electric and magnetic fields to investigate the Stark splitting of all the fine structure levels of the ground multiplet 4f ⁷ (⁸ S) 5d6s ^{2 9} D in Gd I. The tensor polarizabilities were deduced from the level crossing and the rf signals. The variation of the tensor polarizabilities is well reproduced by the LS coupling approximation, except for the small value of the⁹ D ₅ level. A value of the tensor polarizability of the 5d electron is evaluated from the experimental results, ₂(5d)=2.00(6) kHz(kV/cm)². It is shown that the ratio between the electric quadrupole constant and the tensor polarizability is constant, except for the⁹ D ₅ ratio, which is caused by a breakdown of the central field model.     

Stark effect study of the 4f66s2 7 F 1, 2, 3, 4, 5, 6 levels of samarium using nonlinear level crossing technique

The nonlinear level crossing technique with parallel electric and magnetic fields was used to investigate the Stark effect of six levels of the ground multiplet 4f⁶6s^{2 7} F in the Sm I-spectrum. The tensor polarizabilities were deduced from the level crossing signals. The variation of the tensor polarizabilities of the levels of the ground multiplet is well reproduced by the LS coupling approximation, which gives an average value of α₂(F)=?0.88(6) kHz/(kV/cm)² for the six measured levels. The experimental results confirm the validity of the central field approximation in the ground configuration of Sm.     

Precision measurement of the 1s 4f fine structure of HeI

Helium atoms were excited by hydrogen-ion impact, and electric dipole transitions between Stark substates of the 1s 4f multiplet of HeI were induced. Resonance signals were investigated at various frequencies 200 MHz<ν<800 MHz by scanning a static electric fieldF ₀?1 kV/cm and observing the intensity of the impact radiation for the singlet or triplet 1s 3d?1s 2p spectral line. From these measurements the following zero-field transition frequencies of the 1s 4f fine structure were deduced: ν(¹ F ₃?³ F ₂)=232.2(1.0) MHz; ν(³ F ₃?³ F ₄)=214.0(1.3) MHz; ν(¹ F ₃?³ F ₄)=490.6(0.4) MHz. Using calculated parameters of the magnetic fine-structure coupling, the exchange integral 2K=158.0(0.6) MHz of the 1s 4f configuration was evaluated.     

Hyperfine structure in the configurations4f 4 6s 2 and4f 4 5d 6s of Nd I

The high resolution laser-atomic-beam technique was used to investigate the hyperfine structure in Nd I 4f ⁴6s ^{2 5} I,⁵ F,⁵ S and 4f ⁴5d6s ⁷ L,⁷ K,⁷ I,⁷ H. The metastable states were populated by an arc discharge burning in the atomic beam. The measured hyperfine constantsA andB of the levels of 4f ⁴6s ² and 4f ⁴5d6s allow a parametric analysis to be performed using the effective tensor operator formalism. The experimental radial integrals of the 4f and 5d electrons fit with those of the other lanthanides. The 4f radial integrals are in agreement with values of optimized Hartree-Fock-Slater calculations. The spectroscopic quadrupole moments of¹⁴³Nd and¹⁴⁵Nd are deduced from the 4f parameters:Q _I =?0.610(21) b and ?0.314(12) b, respectively. TheQ _I resulting from the 5d parameter are in satisfactory agreement with these values. The hyperfine anomaly due to thes electron in 4f ⁴5d 6s amounts to about 1%.     

Tensor polarizability of cadmium atoms in the excited state (5s5p)3 P 1

The tensor polarizability of the (5s5p)³ P ₁ level of cadmium atoms in a vapour cell were measured using level crossing technique and opto-magnetic double resonance in parallel electric and magnetic fields. The value of the tensor polarizability obtained from the level crossings is: ₂=1.33±0.04 kHz/(kV/cm)² and from the double resonance is: ₂=1.27±0.06 kHz/(kV/cm)². These results were compared with previous theoretical and experimental data of other authors.This work was supported in part by the Committee for Scientific Research under grant No. 2 0226 91 01     

New levels and calculations in the Nd I spectrum

The energies of all the levels of Nd I 4f ⁴ 6s ^{2 5} F and of⁵ S ₂ as well as of 4f ⁴ 5d 6s ⁷ H ₂ have been determined by means of laser-induced fluorescence in a hollow cathode. Their interpretation was carried out with the use of hyperfine structure data and a new parametric calculation of (4f ⁴ 6s ² + 4f ⁴ 5d 6s). Furthermore, the energies andJ values of 5 new odd levels were found.     

Syntheses, structure and rare earth metal photoluminescence of new and known isostructural A2Mo4Sb2O18 (A=Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) compounds

Nine new A₂Mo₄Sb₂O₁₈ (A=Ce, Pr, Eu, Tb, Ho, Er, Tm, Yb, Lu) compounds have been synthesized by solid-state reactions. They are isostructural with six reported analogues of yttrium and other lanthanides and the monoclinic unit cell parameters of all fifteen of them vary linearly with the size of A³⁺ ion. Single crystal X-ray structures of eight A₂Mo₄Sb₂O₁₈ (A=Ce, Pr, Eu, Gd, Tb, Ho, Er, Tm) compounds have been determined. Neat A₂Mo₄Sb₂O₁₈ (A=Pr, Sm, Eu, Tb, Dy, Ho, Er, Tm) compounds exhibit characteristic rare earth metal photoluminescence.     

Tensor polarizabilities of the (nd+(n+1)s)3 2 D 3/2,5/2 levels in Sc I,Y I,La I and Lu I

A technique based on the detection of nonlinear level-crossing resonances in parallel electric and magnetic fields has been extended to the study of the Stark splittings in the hyperfine levels of the ground multiplets (nd+(n+1)s)^{3 2} D _3/2,5/2 in Sc I, Y I, La I, and Lu I. Values of the tensor polarizabilities of thend electrons were evaluated from the experimental results. The variation of the tensor polarizabilities of thend electrons in the configurations under study is discussed. Trends of the polarizabilities in different configurations are compared. The ratio between the electric quadrupole constant and the tensor polarizabilities is constant in La and different in Lu, which is caused by a breakdown of the central field model.     

Synthesis of lanthanide pyrazolonate complexes by the reactions of 1-Phenyl-3-methyl-4-(2,2-dimethylpropan-1-oyl)pyrazol-5-one with metallic lanthanides. Crystal structures of [Ln(Bu t -PMP)3]2 (Ln = Gd, Tb, and Tm)

Lanthanide pyrazolonate complexes Ln(Bu ^t -PMP)₃ (Ln = Pr, Nd, Gd, Tb, Tm, and Lu) are synthesized by the reactions of 1-phenyl-3-methyl-4-(2,2-dimethylpropan-1-oyl)pyrazol-5-one (Bu ^t -PMPH) with metallic lanthanides in the presence of catalytic amounts of the corresponding metal triiodides. The yields of the products are close to quantitative ones. The synthesized compounds can sublime in vacuo (10^?3 Torr) in the temperature range from 235 to 270°C. X-ray diffraction analyses of the sublimed complexes show that they are dimers [Ln(Bu ^t -PMP)₃]₂ (Ln = Gd, Tb, and Tm) in which metal atoms are linked by two bridging pyrazolonate fragments. The coordination environment of the lanthanide is a distorted one-capped trigonal prism.     

Hyperfine structure in the configuration 4f 115d6s 2 of Er I

Hyperfine constants of low lying levels of the configuration 4f ¹¹5d6s ² in Er I have been measured for the only stable odd isotope,¹⁶⁷Er, using high resolution laseratomic-beam spectroscopy. Hyperfine parameters were evaluated from the experimental data using the effective tensor operator formalism. For this purpose eigenfunctions have been determined from an analysis of the fine structure energies of Er I as well as from ab initio multiconfiguration Dirac-Fock calculations. With the latter method also ab initio hyperfine constants for the levels investigated were evaluated. A comparison of calculated fine structure energies, Landég _J -factors and hyperfine constants with the experimental data allowed a test of the reliability of the fine structure and multiconfiguration Dirac-Fock wavefunctions. Effective nuclear electric quadrupole moments for¹⁶⁷Er have been determined from the experimental hyperfine constants using both calculated relativistic electronic radial integrals and hyperfine parameters for the 4f and 5d electrons in the configuration 4f ¹¹5d6s ² in Er I. From a comparison with the nuclear quadrupole moment measured in the mesic atom Sternheimer shielding factors are calculated. Configuration-interaction contributions to the radial integrals 〈r ^?3〉 _nl ⁰¹ of the 4f and 5d electrons have been determined.     

Hyperfine structure in the configurations 4f 13 6s6p and 4f 125d6s 2 of TmI

The laser-atomic-beam spectroscopy has been used to make precise measurements of the hyperfine structure in transitions starting from metastable states of the configuration 4f ¹²5d6s ² in¹⁶⁹TmI. With the resulting experimental magnetic dipole hyperfine constantsA _J andA _J values from former investigations a parametric analysis of the hyperfine structure in the configurations 4f ¹³6s6p and 4f ¹²5d6s ² has been performed using wavefunctions from fine structure calculations. A comparison of theoretical and experimental hyperfine constants allowed a test of the reliability of the wave-functions used. The hyperfine parameters respectively hyperfine radial integrals determined from the analysis were compared with corresponding data from ab initio calculations for the ground configuration in TmI.     

Hyperfine structure and isotope shift of some even parity levels in the YbI spectrum

Using laser induced fluorescence spectroscopy the hyperfine structure of the even parity levels 4f ¹⁴6s6d ³ D ₁, 4f ¹⁴ 6s8s ³ S ₁ and 4f ¹³ 5d6s6p (7/2, 5/2)J=1,2,3 as well as of the odd parity level 4f ¹⁴ 6s6p ³ P ₂ in neutral ytterbium has been investigated. The isotope shift of the transitions 4f ¹⁴6s6p ³ P ₀ → 4f ¹⁴ 6s6p ³ D ₁ and 4f ¹⁴ 6s6p ³ P ₂ → 4f ¹⁴ 6s8s ³ S ₁, 4f ¹³ 5d6s6p (7/2, 5/2)J=1,2,3 could be measured with high accuracy. The results for the 4f ¹⁴ 6s6p ³ D ₁ level show a considerable influence of second order effects of the hyperfine interaction. The isotope shifts of the 4f ¹⁴ 6s8s ³ S ₁ and 4f ¹³ 5d6s6p (7/2, 5/2)J=1 levels indicate a possible configuration mixing for these levels.     

On the hyperfine structure in the configurations 4f n 6s 2, 4f n 5d6s, 4f n 6s6p,and 4f n−15d6s 2 of the lanthanides

A survey of hyperfine analyses in the low-lying configurations 4f ⁿ 6s ², 4f ⁿ 5d6s, 4f ⁿ 6s6p, and 4f ^n?1 5d6s ² of the lanthanides is given. Experimental hf radial integrals 〈r ^?3〉 _nl ^kj are indicated for the configurations under investigation. From a comparison of experimental and theoretical hf radial integrals configuration-interaction contributions Δ _nl ^kj to the hfs have been evaluated for the configurations for which corresponding integrals were available. With nuclear electric quadrupole moments from muonic x-ray investigations and radial integrals 〈r ^?3〉 _nl ⁰¹ and 〈r ^?3〉 _nl ⁰² from experimental hfs quadrupole shielding correctionsR _nl ⁰¹ have been obtained. The variation of hyperfine radial integrals, configuration-interaction contributions and quadrupole shielding corrections over the 4f shell in the configurations under study is discussed. Trends of these quantities in different configurations are compared.     

Stark and Zeeman spectroscopies of 4f 66s6p 7G1-6 levels in Sm I under external electric and magnetic fields

Systematic study of hyperfine structures, Zeeman and Stark effects in Sm I is performed for the lowest ⁷G_1-6 levels belonging to the configuration 4f ⁶6s6p by atomic-beam laser spectroscopy with fluorescence detection. The hyperfine coupling constants of ⁷G_2-6 levels are determined. From the Zeeman splittings for the 4f ⁶6s ^{2 7}F_2-6 ? 4f ⁶6s6p ⁷G_2-6 transitions, g-values are determined for the ⁷G_2.6 levels and the precision is improved by several orders of magnitude. From the Stark splittings for the ⁷F_0-3 ? ⁷G_1-3 transitions, tensor polarizabilities α ₂(J) are determined for the upper ⁷G_1-3 levels. Particularly for the ⁷G₁ level (15 650.55 cm^?1) which has close-lying opposite-parity level, the isotope dependence of α ₂(J) is clearly observed for the first time.     

Radiative lifetimes of levels of the configuration 4f 7 (8 S) 6s 6p in Eu I

Radiative lifetimes of the 4f ⁷ (⁸ S) 6s 6p z ¹⁰ P _{7/2, 9/2},z ⁸ P _{5/2, 7/2, 9/2} andz ⁶ P _{7/2, 5/2} levels of Eu I were measured by the time resolved recording of the exponential decay of the fluorescence. Three of them were measured for the first time, the others agree with previous determinations. From the values of the lifetimes absolute oscillator strengths are deduced, taking into account the branching ratios for the transitions to the 4f ⁷ 6s ² and 4f ⁷ 5d 6s levels. From these absolutef values the radial integralI(6s ², 6s 6p) was derived by a parametric analysis. Theoretical values of oscillator strengths which were calculated using this radial integral show good agreement with the experimental data.     

Hyperfine structure in 5s 4d 3 D —5snf transitions of87Sr

The hyperfine spectra of the 5s4d ³ D ₁-5s20f, 5s4d ³ D ₂-5s23f, and 5s 4d ³ D ₃-5s32f transitions of⁸⁷Sr (I=9/2) have been measured by collinear fast beam laser spectroscopy. The structure in the upper configurations is highly perturbed by fine structure splitting that is of comparable size to the hyperfine interaction energy. These perturbations can be adequately treated with conventional matrix diagonalization methods, using the 5s-electron magnetic dipole interaction terma _5s and the unperturbed fine structure splittings as input parameters. Additionally, hyperfine constants for the lower 5s4d ³ D configurations, including theA- andB-factors and a separation of the individuals- andd-electron contributions to these factors, are derived.     

Hyperfinestructure and isotope shift in the configuration 4f 7 6s8s of Eu I

The investigation of the isotope shift (IS) and hyperfine structure (hfs) is extended from Eu 4f ⁷ 6s7s to the complete configuration 4f ⁷ 6s8s, by means of the transitions 432.3, 456.5, 463.0 and 493.8 nm to 4f ⁷ 6s6p. A thorough experimental and theoretical analysis — including two further lines 492.8 and 498.7 nm from 4f ⁷ 5d ² — is carried out which e.g. confirms former fine structure calculations of one of us (J.F.W.) concerning some reclassifications. The discussion of the IS of the four levels (4f ⁷)6s8s with the sharing rule manifests again the need for inclusion of crossed-second-order effects. For the parameters we evaluated:g ₃(4f, 6s)=?1, 2(2) mK andd=79, 3(1.0) mK. The ratiog ₃/G ₃=?5, 9(1.0)·10^?6 is again in full agreement with those found by us in other Eu configurations. The single electron hfs splitting constantsa _4f ¹⁰ =?2, 3(4) mK,a _6s ¹⁰ =389(4) mK anda _8s ¹⁰ =49 (4) mK were also evaluated and compared to those found in 4f ⁷ 6s7s.     

Carrier-free separation of167Tm from Yb,Er and Ho targets by reversed-phase extraction chromatography and preparation for its medical use

Reversed-phase extraction chromatography employing a Daiflon-supported HDEHP column and HCl as eluent was examined for carrier-free separation of¹⁶⁷Tm from a photo-irradiated Yb target and also from particle-bombarded Er and Ho targets. The examination was performed with radioassays of radioactive Tm and Yb tracers and⁵⁷Co--induced X-ray analysis of Er and Ho. An example of the separation of about 1 mCi of¹⁶⁷Tm from a 100 mg irradiated Yb target enriched in¹⁶⁸Yb and a procedure for the final preparation for medical use are described. The YbSO₄ precipitation could be combined with this chromatographic separation of¹⁶⁷Tm from a more massive Yb target of natural abundance, weighing several tens of grams. A procedure for YbSO₄ precipitation is also presented in the Appendix.     

Crossed-second-order-effects of the isotope shift and hyperfine-structure parameters in the Eu I configuration 4f 7 6s6d

In the Eu I configuration 4f ⁷ 6s6d the isotope shift (IS) and hyperfine-structure (hfs) of the termse ⁶ D ande ¹⁰ D were determined from fourteen transitions (4f ⁷ 6s6d-4f ⁷ 6s6p) with computer supported interference spectroscopy. From the IS of altogether nine levels of 4f ⁷ 6s6d the crossed-second-order-parameterg ₃(4f,6s)=?0.90(6)mK was evaluated. The ratiog ₃/G ₃=?4.4(3)·10^?6 (G ₃: Slater Integral of the fine structure) is of the same size as that from five other independent investigations and one theoretical value. The single electron hfs splitting constantsa _4f ¹⁰ =?1.9(3)mK,a _6s ¹⁰ =391(3)mK, anda _6d ¹² =0.9(3)mK were also evaluated and are compared with those of other Eu 4f ⁷ 6snl configurations.