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     

Precision measurement of the hyperfine structure of Lu175 with the atomic beam magnetic resonance method

The hyperfine structure separations of both doublet states² D _3/2 and² D _5/2 of the ground state configuration 6s ² 5d of Lu¹⁷⁵ have been remeasured with high precision using the atomic beam magnetic resonance method. Magnetic dipole transitions between Zeeman components of the hfs levels were induced applying Ramsey's technique of separated oscillatory fields whenever the field dependence of the resonances was small enough. The hfs intervals at zero field and hfs interaction constants were derived from the measurements. The constants were then corrected for hfs perturbations between the two levels of the doublet. Configuration interaction has been taken into account for the calculation of the dipole matrix elements. The corrected hfs constants are:J=3/2:A=194.332921 (300) MHzB=1511.396 267 (320) MHzC=?70 (19) HzJ=5/2:A=146.776 472 (138) MHzB=1860.656132 (840) MHzC=913 (162) HzD=?16 (24) Hz A quadrupole hfs anomaly between Lu¹⁷⁵ and Lu^176m was not found when comparing the following two ratios: Lu¹⁷⁵:B(5/2)/B(3/2)=1.2310850 (16) Lu^176m :B(5/2)/B(3/2)=1.2310818 (30). So far we have not succeeded in computing an octopole moment from the twoC-factors for the terms² D _3/2,5/2 because the influence of higher configurations could not sufficiently be considered.     

Interpretation of the hyperfine structures in the low even configurations of lanthanum II

The hyperfine structures (hfs) of the levels of the 5d ² and 5d6s configurations of La II, recently measured very accurately by Höhle, Hühnermann and Wagner, are interpreted in the classical parametric scheme. For the magnetic part, the contribution of the two-body far-configuration-mixing effects is determined accurately from the hfs of four levels, and compared with an ab-initio evaluation. For the electric part, all three 5d parameters are determined. The Sternheimer corrections to the radialr ^?3 integral are computed by the Multiconfigurational-Hartree-Fock method, and a corrected value of the electric-quadrupole nuclear moment is deduced:Q(¹³⁹La)=0.20(1) 10^?24 cm².     

Exchange currents in electric transitions and the rôle of siegert's theorem: A case study in deuteron photodisintegration

The hyperfine structure (hfs) splittings of the metastable 1s2s ³ S ₁ state of⁷Li⁺ have been measured with combined laser optical pumping and microwave resonance. A lowenergy Li⁺ ion beam, optically excited by an intersecting laser beam, passed a waveguide where radio frequency transitions were induced. The resulting population transfer among the hfs levels of the³ S ₁ was detected via the change in intensity of the fluorescence light from a second crossing region of laser light and ion beam located past the waveguide. The magnetic hfs constantA(⁷Li⁺, 1s2s ³S₁) was measured and compared with theory. A deviation of the two transition frequenciesν(F=3/2?F=5/2) andν(F=1/2?F=3/2) from the interval rule is due to a depression of theF=3/2 hfs sublevel, caused by mixing of the 2³ S ₁ and 2¹ S ₀ states via hyperfine interaction. This shift was never observed so far in a two-electron spectrum, because of absence ofI>1/2 isotopes in He, the only two-electron atom investigated spectroscopically with high precision. The size of the shift is in fair agreement with a theoretical estimate.     

Hyperfine structure and isotope shift measurements on 235U and laser separation of uranium isotopes by two-step photoionization

Two-step photoionization of an atomic beam and quadrupole mass analysis have been used for the precise measurement of the isotope shift between uranium isotopes 235 and 238 and the hyperfine structure of ²³⁵U. For the 5915 Å ground-state transition 15 hfs components were found. The residual atomic beam was isotopically enriched by factors 2.5 and 10 for ²³⁵U and ²³⁸U, respectively.     

Messung der Hyperfeinstruktur-Aufspaltung des metastabilen3 P 2-Zustandes des Kr83 nach der Atomstrahl-Resonanzmethode

The hyperfine structure splitting of the metastable³ P ₂-state of Kr⁸³ has been measured by the atomic beam magnetic resonance method. A glow discharge served as a source of metastable atoms which were detected by surface ejection of electrons from a metal. In order to improve the signal-to-noise-ratio the magnetic C-field was modulated at a frequency of 37 cps. From the measured splittings the following hfs coupling constants were determined:

$$A(^3 P_2 ) = - (243 \cdot 970 \pm 0 \cdot 004)Mc/sec,B(^3 P_2 ) = - (452 \cdot 12 \pm 0 \cdot 08)Mc/sec.$$     

Measurement of the transverse Doppler shift using a stored relativistic7Li+ ion beam

We have performed for the first time precision spectroscopy on a coasting fast⁷Li⁺ ion beam in a storage ring. The ion beam moving with 6.4% speed of light was first electron cooled and then merged with two counterpropagating laser beams acting on two different hyperfine transitions sharing a common upper level (λ-system). One laser was frequency locked to thea ₃ ¹²⁷J₂ hfs frequency component established as a secondary frequency standard at 514 nm. The second laser was tuned over theλ-resonance, which was recorded relative to¹²⁷J₂ hfs components. This experiment is sensitive to the time dilation in fast moving frames and will lead to new limits for the verification of special relatively. The present status of the experiment and perspectives in accuracy are discussed.     

Bohr–Weisskopf effect: influence of the distributed nuclear magnetization on hfs

Nuclear magnetic moments provide a sensitive test of nuclear wave functions, in particular those of neutrons, which are not readily obtainable from other nuclear data. These are taking added importance by recent proposals to study parity non-conservation (PNC) effects in alkali atoms in isotopic series. By taking ratios of the PNC effects in pairs of isotopes, uncertainties in the atomic wave functions are largely cancelled out at the cost of knowledge of the change in the neutron wave function. The Bohr–Weisskopf effect (B–W) in the hyperfine structure interaction of atoms measures the influence of the spatial distribution of the nuclear magnetization, and thereby provides an additional constraint on the determination of the neutron wave function. The added great importance of B–W in the determination of QED effects from the hfs in hydrogen-like ions of heavy elements, as measured recently at GSI, is noted. The B–W experiments require precision measurements of the hfs interactions and, independently, of the nuclear magnetic moments. A novel atomic beam magnetic resonance (ABMR) method, combining rf and laser excitation, has been developed for a systematic study and initially applied to stable isotopes. Difficulties in adapting the experiment to the ISOLDE radioactive ion beam, which have now been surmounted, are discussed. A first radioactive beam measurement for this study, the precision hfs of ¹²⁶Cs, has been obtained recently. The result is 3629.515(∼0.001) MHz. The ability of ABMR to determine with high precision nuclear magnetic moments in free atoms is a desideratum for the extraction of QED effects from the hfs of the hydrogen-like ions. We also point out manifestations of B–W in condensed matter and atomic physics. This revised version was published online in July 2006 with corrections to the Cover Date.     

Hyperfine structure in the 6p5d configuration and isotope shifts in transitions between the 6s5d and the 6p5d configurations in Ba I

High-resolution laser fluorescence spectroscopy, using a single-mode dye laser acting on a collimated atomic beam, has been performed to determine the hyperfine-structure (hfs) constants in six states of the 6p 5d configuration of¹³⁵Ba and¹³⁷Ba. Isotope shifts (IS) for eleven transitions between the 6s 5d and the 6p 5d configurations have also been measured. From an analysis of the energy levels, intermediate angular wavefunctions have been deduced. The wavefunctions are used to evaluate experimental hyperfine parameters from the experimental hfs constants. The parameters are, for the magnetic-dipole interaction compared with theoretical values, and for the electricquadrupole interaction used to estimate the nuclear quadrupole moments for the odd isotopes. The IS in the measured transitions are analysed using a King-plot, with the first resonance line in Ba II as the reference. Specific mass and field shifts are evaluated for the measured transitions. The field shifts have been used to determine the change in mean-square radius between the natural abundant Ba-isotopes.     

Hyperfine structure in optical spectra of LiYF4-Ho

We report high resolution infrared absorption spectra of LiYF₄-Ho exhibiting well resolved nuclear hyperfine structure (hfs). The halfwidths of some hfs components do not exceed 0.03 cm^?1. Magnetic field at the nucleus is evaluated. Non-radiative relaxation rates due to phonon emission are estimated. With the help of experimentally found 〈Γ₃|J_z|Γ₃〉 matrix elements g-factors of the excited crystal field levels are calculated. Some hfs peculiarities are discussed.     

Spin and magnetic moment of25Na by β-radiation detected optical pumping

²⁵Na (T_1/2 = 60 sec) has been produced in a²²Ne target by the (α,p) reaction and polarized by means of spin-exchange scattering with optically pumped⁸⁷Rb. The asymmetry in the β decay of polarized nuclei served to detect rf transitions between hfs Zeeman levels of the atomic ground state, yielding spinI = 5/2 and hyperfine splitting ΔW= 2648.5(3.0) MHz, from which the magnetic moment μ_I = 3.683(4)nm (corrected for diamagnetism) was deduced.     

High resolution measurements of the hyperfine structure of atomic Lanthanum for energetically low lying levels of odd parity

Doppler-reduced saturation absorption spectroscopy is applied to study the hyperfine structure of excited levels of Lanthanum. 16 transitions in the near infrared wavelength range are investigated. Precise values for the magnetic dipole hyperfine structure constants A as well as for the electric quadrupole hyperfine structure constants B of the isotope ¹³⁹La are determined for 14 levels of odd parity and nine levels of even parity. For levels of even parity a good agreement is found with values from previous measurements using sub-Doppler methods. For levels of odd parity previously determined values are improved and for two levels new values of the hyperfine structure constants are reported.     

Radio-frequency spectroscopy in the states3 D 3,2 of platinum

The magnetic dipole hyperfine interaction constantsA of the atomic ground state³ D ₃ and of the first excited state³ D ₃ in¹⁹⁵Pt have been measured by atomic beam magnetic resonance. The electronicg _J factors of these states were determined from the Zeeman splitting in¹⁹⁴Pt. Using intermediate coupling wave functions derived for the configurations (5d+6s)¹⁰ effective hyperfine radial integrals are evaluated.     

A new method for the production of atomic beams of highly refractory elements and first atomic beam magnetic resonances in Ta181

A new universal method for the production of atomic beams of highly refractory elements has been developed. The beams of free atoms are produced by locally heating a small area on a target consisting of the material to be evaporated. The local heating is achieved via the focussed electron beam of a commercial electron gun. The atomic beams so obtained are suitable for studying hyperfine structures by the atomic beam magnetic resonance method. The first observedrf resonances in the ground state⁴ F _3/2 and the first excited state⁴ F _5/2 of Ta¹⁸¹ are reported.     

High precision measurements of the hyperfine structure of seven metastable atomic states of57Fe by laser-Rf double-resonance

The hyperfine structure of the metastable atomic states (3d ⁷4s)⁵ F _2,3,4,5 and (3d ⁷ 4s)³ F _2,3,4 of⁵⁷Fe has been measured using theABMR- LIRF method (atomic beam magnetic resonance detected by laser induced resonance fluorescence). From these measurements the following hfs constantsA of the magnetic dipole interaction have been obtained (corrected for second order effects):A(⁵ F ₂)=55.994(7) MHzA(⁵ F ₃)=69.632(5) MHzA(⁵ F ₄)=78.435(4) MHzA(⁵ F ₅)=87.246(3) MHzA(³ F ₂)=143.328(4) MHzA(³ F ₃)=50.602(10) MHzA(³ F ₄)=13.456(5) MHz     

Nuclear reactions as an example of the quantum theory of irreversible processes

A modification of the atomic beam magnetic resonance method for investigation of the hyperfine structure of excited atomic states will be described. Radiofrequency transitions between the hyperfine structure niveaus of the excited state, which are unequally populated by circularly polarized light, are detected by observing the resulting change in population number of the hyperfine structure niveaus of the ground state using magnetic deflection in an inhomogeneous field and additional radiofrequency transitions in the ground state as analyzers. As an application the hyperfine structure of the excited 4² P _3/2-state of K³⁹ has been investigated in an almost strong magnetic field of about 65 G with a constant frequency of the applied radiofrequency field of 125.50 Mc/s. The analysis of the radiofrequency signal of the excited state detected as a change in the amplitude of a radiofrequency transition in the ground state yielded the valuesA=(6.10±0.25) Mc/s andB=(1.8±1.2) Mc/s for the hyperfine structure constants of the 4² P _3/2-state of K³⁹. Further possibilities for observing signals of the excited state with the apparatus used in this experiment are also discussed.     

Hyperfine structure measurements in metastable states of165Ho

The hyperfine structure constants and the electronic g _J factor of the state 4f ¹¹ 6s ^{2 4} I _11/2 belonging to the holmium ground multiplet have been measured using the atomic beam magnetic resonance technique combined with a state-selective laser-induced detection of the resonant atoms. By the same method the g _J factor of the level 4f ¹¹6s ²⁴ I _9/2 was determined, while the hyperfine structures of this metastable state and of two high-lying even parity states have been investigated by high resolution laser spectroscopy. The results for the experimentalA andB factors of all four members of the ground multiplet allow a least-squares evaluation of the three magnetic dipole and the three electric quadrupole effective radial parameters for the configuration 4f ¹¹ 6s ² of holmium, yielding an accurate value for the spectroscopic nuclear electric quadrupole moment:Q _hfs(¹⁶⁵Ho)=2.716(9)b (uncorrected for quadrupole shielding). From a comparison to the quadrupole moments measured in mesic holmium atoms the shielding factor could be estimated.     

Parity nonconservation in hydrogen

We discuss the prospects for parity violation experiments in atomic hydrogen and deuterium to contribute to testing the Standard Model (SM). We find that, if parity experiments in hydrogen can be done, they remain highly desirable because there is negligible atomic-physics uncertainty and low energy tests of weak neutral current interactions are needed to probe for new physics beyond the SM. Analysis of a generic APV experiment in deuterium indicates that a 0.3% measurement of C _1D requires development of a slow (77K) metastable beam of ???5×10¹⁴D(2S)s ^???1 per hyperfine component. The advent of UV radiation from free electron laser (FEL) technology could allow production of such a beam.     

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.