Charge radius change in the heavy tin isotopes until A = 132 from laser spectroscopy

Laser spectroscopy measurements have been carried out on the very neutron-rich tin isotopes with the COMPLIS experimental setup. Using the 5s ²5p ²³ P ₀ → 5s ²5p6s ³ P ₁ optical transition, hyperfine spectra of ^126-132Sn and ^{125m, 127m, 129m-131m}Sn where recorded for the first time. The variation of the mean-square charge radius ( δ〈r ²〉) between these nuclei and nuclear moments of the isomers and the odd isotopes were thus measured. An odd-even staggering which inverts at A = 130 is clearly observed. This indicates a small appearance of a plateau on the δ〈r ²〉 which has to be confirmed by measuring the isotope shift beyond A = 132. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: leblanc@ipno.in2p3.fr     

Hyperfine splitting and isotope shift in the atomic D2 line of 22,23Na and the quadrupole moment of 22Na

The hyperfine structure of the D₂ optical line in ²²Na and ²³Na has been investigated using high resolution laser spectroscopy of a well-collimated atomic beam. The hyperfine splitting constants A and B for the excited 3p ²P_3/2 level for both investigated sodium isotopes have been obtained. They are as follows: A(22) = 7.31(4) MHz, B(22) = 4.71(28) MHz, A(23) = 18.572(24) MHz, B(23) = 2.723(55) MHz. With this data, using the high precision MCHF calculations for the electric field gradient at the nucleus, the electric quadrupole moment of ²²Na has been deduced: Q_s(22) =+0.185(11) b. The sign of Q_s(22), determined for the first time, indicates a prolate nuclear deformation. A precise value of the isotope shift ^22,23Na in the D₂ line has also been obtained. Received: 26 February 1998 / Revised version: 25 June 1998     

Reanalysis and semi-empirical predictions of the hyperfine structure of in the model space

On the basis of most of the earlier hyperfine-structure (hfs) experimental results, the hfs of the atomic zirconium has been reanalyzed by the simultaneous parameterization of the one- and two-body interactions for the model space (4 d + 5 s ) ⁴ . The values of the one- and two-body hfs parameters have been determined and the nuclear quadrupole moment, free of Sternheimer corrections up to second order, has been evaluated. Moreover, the values of the magnetic-dipole A and the electric-quadrupole B constants for all known levels of this model space have been predicted. Received: 22 December 1997 / Revised: 15 May 1998 / Accepted: 1 July 1998     

Hyperfine splitting and isotope shift in the optical transition of Eu isotopes and electromagnetic moments of Eu

The laser-induced resonance fluorescence in an atomic beam was used in order to measure the hyperfine splitting of the 4f ⁷ 6s ² and 4f^{7 6s6p} levels in ^151,153,155Eu isotopes. The hfs constants A and B of the unstable ¹⁵⁵Eu were determined for the first time: MHz, MHz and MHz. With these data and after corrections for second-order hyperfine structure perturbations the nuclear moments of ¹⁵⁵Eu were deduced: n.m. and b. In addition new and more precise values of the hfs constants of the excited state for the stable ^151,153Eu were obtained. They are as follows: MHz, MHz and MHz, MHz. The hyperfine anomalies % and % were extracted from the corrected hfs constants. Received 28 July 1999 and Received in final form 14 January 2000     

Finestructure, hyperfine structure and isotope shift of 4f 6s7s in Er I

The isotope shift (IS) and hyperfine structure (hfs) of nine levels (31720 to 38921 cm^-1) assigned to the configuration 4 f ¹² 6 s 7 s in neutral erbium have been determined experimentally using Doppler-reduced saturation absorption spectroscopy in a gas discharge. We performed a fine structure analysis in the SL-coupling scheme of the single configuration 4 f ¹² 6 s 7 s, confirming and extending the classification of even parity Er I levels. We discriminated the different hfs contributions of the 4f¹² core and the (6 s +7 s) outer electrons of the shell in a non-relativistic JJ-coupling approach and in the relativistic effective tensor operator formalism in SL-coupling. The relativistic one-electron parameters of the hfs for ¹⁶⁷Er were fitted to the experimental data by a least squares fit procedure: [0pt] a ⁰¹ _4f =-147(3) MHz, [0pt] a ¹⁰ _6s + a ¹⁰ _7s =-1840(30) MHz, [0pt] b ⁰² _4f =6560(80) MHz. The level dependencies of the isotope shift were evaluated based on crossed second order (CSO) effects. We obtained the following results for the CSO parameters for the isotope pairs ^170-168Er: d _6s7s =-740(30) MHz, z _4f = 0(5) MHz, ( g _3,6s ( f , 6 s )+ g _{3, 7s} ( f , 7 s ))= -24(15) MHz and for ^170-166Er: d _6s7s =-1500(50) MHz, z _4f =0(10) MHz, ( g _3,6s ( f ,6 s )+ g _3,7s ( f +7 s ))=-50(29) MHz. The resulting parameters for the hfs are compared with those known for other configurations of the Er atom and ion. Received 16 May 1999 and Received in final form 31 January 2000     

Nuclear size correction to the hyperfine splitting in low- hydrogen-like atoms

The finite nuclear size effect on the hyperfine splitting of low-Z hydrogen-like atoms is studied in the external field approximation. A simple non-relativistic formula is proposed which expresses the nuclear size correction to the hyperfine splitting in terms of moments of the nuclear charge and magnetization distribution. The numerical results obtained via this formula are compared with corresponding results derived by means of the Zemach formula. A relativistic formula for the nuclear size correction to the hyperfine splitting is also derived. Received 18 March 2002 / Received in final form 14 November 2002 Published online 28 January 2003 RID="a" ID="a"e-mail: plunien@physik.tu-dresden.de     

Doppler limited laser spectroscopy on hafnium lines. Part II: Hyperfine structure of odd-parity levels

The hyperfine structure of selected odd-parity levels of the configurations 5d6s ^26p and 5d ^26s6p of I was studied in 10 lines lying in the red spectral region. Hyperfine spectra were obtained by the method of laser induced fluorescence in the plasma of a liquid nitrogen cooled hollow cathode discharge. The observed hyperfine structure constants A and B, together with results from earlier studies were analyzed by means of a parametric method. The interpretation has been carried out based on a refined multiconfigurational fine structure calculation including the main Rydberg series configurations mutually interacting. The set of fine structure parameters as well as the leading eigenvector percentages of levels relevant for this paper are given. The following single electron hfs parameters were deduced for : , ,, for the lowest configuration. Received: 16 November 1998 / Received in final form: 5 February 1999     

Hyperfine structure in the atomic spectrum of niobium

We report on hyperfine structure measurements in 21 lines of atomic niobium in the spectral region from 640 nm to 870 nm by means of optogalvanic laser spectroscopy and laser induced fluorescence spectroscopy using a hollow cathode discharge and a tunable single-mode cw ring laser. Hyperfine structure constants A and B of altogether 29 excited energy levels were determined, 18 of them for the first time. Received 18 July 2002 / Received in final form 8 November 2002 Published online 4 February 2003 RID="a" ID="a"e-mail: sk@kalium.physik.tu-berlin.de     

High-resolution LIF measurements on hyperfine structure and isotope shifts in various states of Lu I using the second and third harmonic of a cw Ti:sapphire laser

With the second and third harmonic of a tunable single-mode cw Ti:S laser, generated inside external enhancement cavities, high-resolution LIF measurements on several states of Lu I in various parts of the electromagnetic spectrum are performed. From these measurements, hyperfine structure A and B constants for both ¹⁷⁵Lu and ¹⁷⁶Lu as well as isotope shifts have been determined for all levels observed in the single-step excitation process. From the measured A constants, the magnetic hyperfine structure anomaly has been derived for various states. Received 14 January 2002 Published online 19 July 2002     

Fine and hyperfine structure in the atomic spectrum of niobium

A parametric analysis of the fine and the magnetic dipole hyperfine structure for the three configurations of odd parity 4d³5s5p, 4d⁴5p and 4d²5s²5p was performed. Effective one-electron parameters were determined and theoretical predictions are given for the magnetic dipole hyperfine structure constants A for the levels of these three configurations. Additionally, 12 new energy levels could be found, four of odd and eight of even parity, by re-analysing data for experimental wavelengths of Nb.     

Precise measurement of hyperfine coupling in CH F based on nuclear spin conversion

A new method is proposed for the experimental determination of the hyperfine coupling in molecules. The method is based on the level-crossing effect in the spin isomer conversion in alternating electric fields. An experiment performed with the ¹³CH₃F molecules has revealed the strength of the off-diagonal in K () nuclear spin-spin coupling kHz, which is only by kHz larger than the theoretical value calculated on the basis of the molecular structure. Received 25 January 2000 and Received in final form 11 May 2000     

Further experimental investigation of the hyperfine structure in the spectrum of atomic niobium

Laser spectroscopy with either optogalvanic or laser induced fluorescence detection have been employed to measure the hyperfine structure of 25 transitions of atomic niobium in the visible and near infrared spectral range. The magnetic dipole hyperfine interaction constants A of 43 energy levels (22 of even and 21 of odd parity) were determined, 30 of which have been investigated for the first time. The values obtained for the even parity levels are compared with the results of a parametric analysis.     

Isotope effect for transport and magnetic properties of La 0.35 Pr 0.35 Ca 0.3 MnO 3 thin films

The effect of ¹⁶ O → ¹⁸ O isotope substitution on electrical resistivity, magnetoresistance, and ac magnetic susceptibility was studied for La_0.35Pr_0.35Ca_0.3MnO₃ epitaxial thin films deposited onto LaAlO₃ and SrTiO₃ substrates. For the films on LaAlO₃, the isotope substitution resulted in the reversible transition from a metal-like to insulating state. The applied magnetic field ( H ≥ 2 T) transformed the sample with ¹⁸O back to the metallic state. The films on SrTiO₃ remained metallic at low temperatures for both ¹⁶O and ¹⁸O, but the shift of the resistivity peak corresponding to onset of metallic state exceeded 63 K after ¹⁶ O → ¹⁸ O substitution. The temperature dependence of both resistivity and magnetic susceptibility was characterized by hysteresis, especially pronounced in the case of the films on LaAlO₃. Such a behavior gives certain indications of the phase separation characteristic of interplay between ferromagnetism and charge ordering. Received 11 February 2000 and Received in final form 13 September 2000     

Investigation of the magnetic rotation in 196Pb

Lifetimes for low-lying members of the irregular ΔI = 1 band in ¹⁹⁶Pb have been measured by means of the EUROBALL spectrometer using the coincidence recoil distance technique. The ¹⁶⁴Dy(³⁶S,4n)¹⁹⁶Pb reaction at a beam energy of 168 MeV was used. The data were analyzed with the differential decay-curve method (DDCM). A characteristic drop in the reduced transition probabilities with increasing angular momentum was observed in agreement with predictions by the semiclassical model for the shears mechanism. Received: 3 May 2001 / Accepted: 20 June 2001     

Experimental determination of spin-rotation and spin-spin magnetic interactions in by nuclear spin conversion

When a gas sample of ¹³CH₃F is prepared with a population of isomers (ortho and para forms) far from the equilibrium given by nuclear spin statistics, it relaxes towards this equilibrium with an exponential decay rate. This phenomenon called nuclear spin conversion is mainly governed by intramolecular spin-spin and spin-rotation interactions. In the quantum relaxation model [P.L. Chapovsky, Phys. Rev. A 43, 3624 (1991)], two pairs of ortho-para levels (J = 9, K = 3; J' = 11, K' = 1) and (J = 20, K = 3; J' = 21, K' = 1) are principally responsible for the conversion. The levels of the second pair are coupled by both spin-spin and spin-rotation interactions. The application of an electric field (up to 10 kV/cm) induces a crossing of the Stark components of this pair, which is observed for the first time. A specific experimental set-up based on an electric field of alternating triangular shape is used, which allows the determination of the strength of both interactions via the measurement of the spin conversion decay rates. This work yields the first experimental value for the electronic contribution to the spin-rotation interaction in ¹³CH₃F. Received 23 May 2002 / Received in final form 18 September 2002 Published online 21 January 2003 RID="a" ID="a"e-mail: Patrice.Cacciani@univ-lille1.fr     

Magnetic moments for lithium quartet S states

The fully correlated calculations of the Zeeman g_J factors for the first three quartet S states of lithium are presented, including relativistic and radiative corrections of orders α², α² m/M, and α³. The isotope shifts in g_J are predicted precisely for various isotopes of lithium. Received 4 December 2000 and Received in final form 26 September 2001     

Hyperfine structure and isotope shift measurements on 4d10 1S0 → 4d9 5p J=1 transitions in Pd I using deep-UV cw laser spectroscopy

The 4 d ^{10 1} S₀ ground-state transitions to the 4 d ⁹ 5 p configuration of palladium (Pd) have been studied. For this purpose, a tunable, single-mode, deep-UV cw laser has been built to generate the sum frequency of a frequency-doubled Ti:S laser with a second Ti:S laser. The produced wavelengths range from 244 to 276 nm. From the measured spectra the frequency splitting due to hyperfine structure and isotope shift, the hyperfine structure A and B constants and the lifetimes of the states have been extracted. Received 3 October 2001     

Multiple Coulomb excitation of a 70Ge beam and the interpretation of the 02 + state as a deformed intruder

Electromagnetic properties of the low-lying states in a ⁷⁰Ge nucleus were studied through the multiple Coulomb excitation of a ⁷⁰Ge beam with a ^natPb target. Relative γ-ray intensities were measured as a function of emission angle relative to the scattered projectile. Sixteen E2 matrix elements, including diagonal ones, for 6 low-lying states have been determined using the least-squares search code GOSIA. The expectation values 〈Q ²〉 of 0₁ ⁺ and 0₂ ⁺ states in ⁷⁰Ge are compared with those in ^{72, 74, 76}Ge. Simple mixing calculations indicate that the 0₂ ⁺ states in ⁷⁰Ge and ⁷²Se can be treated as deformed intruder states. It is shown that the deformed intruder becomes the ground state in ⁷⁴Kr. These interpretations of the 0₂ ⁺ states in this region are compared with the potential-energy surface calculations by the Nilsson-Strutinsky model, which allow to interpret the experimental results in a qualitative way from the theoretical point of view. Received: 2 September 2002 / Accepted: 5 November 2002 / Published online: 25 February 2003 RID="a" ID="a"e-mail: sugawara@pf.it-chiba.ac.jp Communicated by D. Schwalm     

Isotope shift studies in the first spectrum of dysprosium: confirmation of assignments to and new assignments to configuration

Isotope shifts (-) are reported for 221 spectral lines of the neutral dysprosium atom (Dy I) in the region 470-565 nm using a photoelectric recording Fabry-Perot spectrometer and highly enriched isotopic samples of and excited in liquid-nitrogen-cooled hollow-cathode lamps. Isotope shift data for 173 of these lines are being reported for the first time. Using the isotope shift data, term isotope shifts (-) have been evaluated for 99 even- and 68 odd-parity energy levels of Dy I. New values have been obtained for 24 odd and 36 even levels. These new values have enabled us to check some of the existing tentative assignments and also to suggest configuration assignments to a few unassigned energy levels. The earlier tentative assignments of 4 f10 5 d 6 p configuration to many high odd levels lying above have been presently confirmed. We could assign the 4f^95d6s6p configuration to 24 unassigned even levels. Received: 3 August 1998     

Measurement of quadrupole moment of the 134 keV level in <Superscript>131</Superscript>Cs

The time differential as well as time integral perturbed angular correlations of the 486-134 keV cascade in ¹³¹Cs have been studied in a polycrystalline BaSO₄ powder source using a HPGe-BaF₂ detector system. The fundamental quadrupole frequency for the 134 keV level has been found to be ω₀= (4.4 ± 0.4) × 10⁷ rad/s. From a comparison of the quadrupole frequencies of this level and that of the 81 keV level in ¹³³Cs, measured earlier in the same crystalline environment of the source, the absolute value of the quadrupole moment of the 134 keV level in ¹³¹Cs has been found to be 0.022 ± 0.002 b. This value of the quadrupole moment is reported for the first time and compared with the value predicted theoretically within the unified nuclear model with intermediate coupling. Received: 21 October 1999 / Revised version: 22 December 1999