The magnetic moments of (vg 9/2)-levels in odd Zn isotopes

^69m,71mZn have been implanted with an isotope separator on-line into a cold iron host matrix. Nuclear magnetic resonance of the low-temperature oriented isotopes has been observed. The resonance frequencies for zero external magnetic field are v_L(^69mZnFe@#@) =36.814(35) MHz andv _L (^71mZnFe)=33.47(19) MHz. From these the magnetic moments of the 9/2⁺ iosmeric states have been derived as μ(^69mZn)=(?)1.138(18) n.m. andμ(^71mZn)=(?)1.035(18) n.m. The experimentally known magnetic moments of (vg _9/2)-levels in odd zinc isotopes are compared to theoretical estimates.     

Multipole mixing ratios of transitions in175Lu populated from the decay of175Hf

Electron capture decay of¹⁷⁵Hf(70 d) provides a possibility for unambiguous determination of the sign and magnitude of multipole mixing ratios for 89 keV and 114 keV transitions in¹⁷⁵Lu. This is because both gamma rays are in coincidence with the 230 keV transition which is of a pureE2 character. The results of theγ —γ directional correlation measurements, in terms ofE2/M1 mixing ratiosδ, areδ ₈₉ = 0.11±0.07 andδ ₁₁₄ = 0.465±0.005. In addition the directional correlation measurements of the 89γ- 343γ and 319γ-114γ cascades yieldδ ₃₄₃ = 0.08±0.07 andδ ₃₁₉ = ?0.152±0.015.Radioactivity ¹⁷⁵Hf from¹⁷⁴Hf(n, γ); measuredγ —γ(θ) deducedδ(E2/M1); Ge(Li) detectors.     

The magnetic moments and halflives of the 5/2− states in199Hg and197Hg and the discrepancies in the experimental hyperfine fields at Hg in Fe

The Larmor-precession frequencies for¹⁹⁷Hg in Fe have been determined to beω _L = 1291 ±25 MHz at 293 K andω _L = 1334±25 MHz at 105 K. For¹⁹⁹Hg in Feω _L =1372±50 MHz has been measured at 293 K. The half-lives of the 5/2^? states in¹⁹⁷Hg and¹⁹⁹Hg have been remeasured asT _1/2(¹⁹⁷Hg)=8.1±0.16 nsec andT _1/2(¹⁹⁹Hg)=2.45±0.05 ns, respectively. The magnetic moment of the 5/2^? 158keV state in¹⁹⁹Hg was redetermined by the integral perturbed angular correlation method in an external magnetic field of 47kG asμ(5/2 ^? ) = 0.905±0.091 nm. With this new value consistency for the magnetic hyperfine fields at Hg in Fe measured with the TDPAC-method and with the NMR/ON-method is obtained. This fact is used to determine theg-factors of the 5/2^? states in¹⁹⁷Hg and¹⁹⁹Hg more precisely fromω _L -values given above:g(¹⁹⁷Hg)=0.342(6);g(¹⁹⁹Hg)=0.352(13). The magnetic moments of the first excited 2⁺ states in^198–204Hg isotopes which rely on calibrations with the¹⁹⁹Hg-g-factor, are revised.     

Analysis of the isotope shifts and hyperfine structure in the 3 988 Å (6s6p 1 P 1↔6s 2 1 S 0) YbI line

High-resolution laser spectroscopy using a pulsed dye-laser acting on a collimated atomic beam has been used to determine the isotope shifts in the 3 988 Å YbI line. The following results have been obtained:Δσ(176, 174)=?509(4)MHz,Δσ (174, 173)=?291(10) MHz,Δσ(174, 172)=?530(4) MHz,Δσ(172, 171)=?414(5) MHz andΔσ(172, 170)= ?665(10) MHz. The sign of the magnetic dipole interaction constant in the¹ P ₁ state for¹⁷¹Yb is found to be negative,a(¹ P ₁, 171)=?213.4(3.0) MHz. The electric quadrupole interaction constant for¹⁷³Yb in the¹ P ₁ state is found to beb(¹ P ₁, 173)=605(20) MHz.     

Measurement of the Lamb shift 42S1/2-42P1/2 of the helium ion

Helium ions were produced in then=4 states by electron collisions with ground state atoms, resulting in simultaneous ionization and excitation. Dipole transitions between the Zeeman levels of the states 4² S _1/2 and 4² P _1/2 were induced by a microwave electric field. The intensity of the emitted Fowlerα line 4686 Å, corresponding to transitions from then=4 to then=3 states was then reduced by about 3%. From the measurements, a value of the Lamb shiftδ=1751±25 MHz was obtained, compared with the theoretical valueδ=1768.23±0.55 MHz, and the results ofLea, Leventhal andLamb ofδ=1765±20 MHz.     

Untersuchung der Hyperfeinstruktur des 62 P 1/2-Zustandes von133Cs im starken Magnetfeld mit der optischen Doppelresonanzmethode

The hyperfine structure of the 6² P _1/2-state of¹³³Cs has been measured by optical double resonance in a strong magnetic field. From the positions of the magnetic dipole transitionsδm _J =±1,δm _I =0 theg _J -factorg _J(6² P _1/2)=0.66590(9) and the magnetic hfs-coupling constanta(6² P _1/2)=291.90(12) MHz could be derived.     

Collinear laser spectroscopy on108g, 108m In using an ion source with bunched beam release

The hyperfine structure and isotope shift of^108gIn and^108mIn have been investigated by means of collinear fast-beam laser spectroscopy in the resonance line atλ=451 nm. The indium isotopes were prepared at the GSI on-line mass separator following a fusion evaporation reaction. For the first time, a FEBIAD ion source with bunched release of indium was used. Magnetic dipole moments, electric quadrupole moments and isotope shifts were determined. The present results lead us to assign the spinI=2 to the¹⁰⁸In (T _1/2=40 min) state. Spins and moments are discussed in the framework of thejj-coupling model.     

Multipole mixing ratios of γ-transltions in 182W

γ-γ directional correlation experiments were performed on 14 cascades in ¹⁸²W populated from the β^? decay of ¹⁸²Ta(115 d). Two Ge(Li) detectors were used in a coincidence arrangement, and the ¹⁸²Ta sources were dissolved in HF acid to minimize extranuclear perturbations. For the 1189keV, 2^? → 2⁺ transition, the measured directional correlation coefficients are consistent only with multipole mixing ratios $\text{δ}\text{(}\text{M}\text{2}\text{E}\text{1)}\text{= 0.45 ± 0.03}\text{and}\text{δ}\text{(E3}\text{E1)}\text{= ?0.67 ± 0.07}$. These mixing ratios are discussed and compared with the known conversion coefficients for the 1189keV transition. The E2/M1 multipole mixing ratios determined are (energy in keV): δ(66) = 0.15 ± 0.15, δ(85) = 0.31 ± 0.05, δ(114) = 0.31 ± 0.05, 0.56 ≦ δ(179) ≦ 1.36, δ(1121) = 12⁺²_?1, and δ(1231) = ?(32⁺¹⁴²_?15). The measured M2/E1 mixing ratios are: δ(68) = 0.03 ± 0.02, δ(152) = 0.014 ± 0.013 and δ(156) = ?0.13 ± 0.19.     

Relativistic J-dependence of the isotope shift in the 6s-6p doublet of Ba II

The collinear laser-ion beam technique has been used to measure the isotope shift and hyperfine structure in the 6s-6p doublet (4,934Å, 4,554Å) of Ba II for all seven stable isotopes. The influence of the excited² P _1/2 and² P _3/2 states on the field shift leads to a difference of 2.5(3)% in the electronicF factors. The specific mass shifts differ by {A′-A} 2.2(3) MHz which corresponds to about 12% of the normal mass shift.     

Determination of the isotope shift in theD 1 line between197Au and195Au

The isotope shift between¹⁹⁷Au (stable) and¹⁹⁵Au (T _1/2=183 d) was determined by resonance fluorescence and polarization spectroscopy in the 6s² S _1/2 -6p ² P _1/2, λ =267.6nm line. The result is δν^{195, 197}=-2.9(2) GHz corresponding to a change of the mean-square charge radius by δ〈r ²〉^{195, 197}=0.063(9) fm². The sample was confined to a resonance cell heated to temperatures of up to 1500°C.     

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.     

Nuclear moments and optical isotope shifts of108m Ag and110m Ag

The hyperfine structure of the resonance lines of^108m Ag and^110m Ag has been investigated by means of optical interference spectroscopy. The metastable isotopes were produced by neutron irradiation in a reactor. From the measureda- andb-values we derive the value for the nuclear magnetic dipole moment of^108mAgμ _I (108m)=3.577 (20)μ _n and the values for the electric quadrupole momentsQ _I (108m)=1.52(8) bQ _I (110m)=1.65(10) b (without Sternheimer correction). The measured isotope shifts allow the determination of the changes in the mean square charge radii of the nuclei involved:δ 〈r ²〉(108m-107)=0.022(3)fm² δ 〈r ²〉(110m-109)=0.029(2)fm². The isotope positions show odd-even staggering comparable with those of neighbouring isotonic nuclides.     

Determination of spin,magnetic moment and isotopic shift of neutron rich205Hg by optical pumping

Neutron rich²⁰⁵Hg (T _1/2=5.2 min) was produced and on-line mass separated at the ISOLDE facility at CERN. The polarization achieved by optical pumping via the atomic line (6s ²¹ S ₀?6s6p ³ P ₁,λ=2 537Å) was monitored by theβ decay asymmetry. Hyperfine structure and isotopic shift of the²⁰⁵Hg absorption line was determined by Zeeman scanning. In addition a magnetic resonance was performed on the polarized²⁰⁵Hg nuclei in the atomic ground state. The results are: \(I(^{205} Hg) = \tfrac{1}{2}\) (confirmed);μ _I (²⁰⁵Hg)=0.5915 (1)μ _N (uncorrected for diamagnetism); isotopic shiftδv^204/205=v(²⁰⁵Hg)-v(204Hg)=?1.8 (1) GHz.μ _I and IS are discussed briefly in the frame of current literature.     

Isotopieverschiebungskonstanten von Th,U, Pu und Am

The isotope shifts of unperturbed electron configurations have been determined from isotope shift measurements in the spectra of Th, U, Pu, and Am. The screening of the 7s electron charge density at the nucleus by 6d, 7s, and 7p electrons is discussed. It turns out that the same screening factors as for the 6s electron in lighter elements can be used. The screening of the 7s electron charge density at the nucleus by one 5f electron amounts to about 25%: [δT(f ⁿ s)?δT(f ⁿ )]/[δT(f ⁿ }s)?δ(f ^n} )]=0.7₅. The charge density at the nucleus due to the filleds (andp _1/2) shells is considerabely screened by anf electron. The isotope shiftδT(f^n}-1 d ^m +2)?δT(f ⁿ d ^m ) produced by this effect is of the same order of magnitude as the isotope shiftδT(f ⁿ d ^m s)-δT(f ⁿ d ^m ) due to ans electron. The experimental isotope shift constants are found to be:Β C _exp(Th²³⁰–Th²³²)=880±120;Β C _exp(U²³³–U²³⁵)=1000±180;Β C _exp(U²³⁴–U²³⁶)=1070±200;Β C _exp(U²³⁶–U²³⁸)=1080±180;Β C _exp(Pu²³⁸–Pu²⁴⁰)=1200±120;Β C _exp(Pu²³⁹–Pu²⁴¹)=1060±100;Β C _exp(Pu²⁴⁰–Pu242)=900 ±90;Β C _exp(Am²⁴¹–Am²⁴³)=890±50 [10^?3cm^?1]. The ratiosΒ C _exp/C _th are discussed.     

Spins,moments and charge radii in the isotopic series181Hg-191Hg

The hyperfine structure splitting and the isotope shift in the (6 s^{2 1}S₀ - 6s 6p³P₁,λ=2,537 Å) line of very neutron deficient Hg isotopes were determined by the β radiation detected optical pumping method (β-RADOP). In addition, nuclear magnetic resonance was observed in the atomic ground state. The results are Mean-square nuclear charge radii are calculated. Interpreting the sudden change of nuclear radius between¹⁸⁷Hg and¹⁸⁵Hg δ〈r²〉^187,185=0.42(5)fm² as oblate-prolate shape transition, one obtains δ〈β²〉 =0.054(5).     

NMR detected by Mössbauer-effect,applied to the system57CoFe

The ratio of the Larmor frequencies of¹¹¹Cd and²H has been measured in an aqueous solution of CdSO₄ with high accuracy.¹¹¹Cd chemical shifts have been investigated in aqueous solutions of CdCl₂, Cd(NO₃)₂, CdSO₄, and Cd(ClO₄)₂ as a function of concentration. Using these, the ratio of the Larmor frequencies of the¹¹¹Cd nuclei for infinite dilution relative to²H in pure D₂O is given. From this ag _I -factor for¹¹¹Cd has been derived and has been compared with theg _I -factor of an optical pumping experiment. The resulting shielding constant is σ^*(hydrated¹¹¹Cd versus¹¹¹Cd atom)=?1.106(4) · 10^?3. This yields an atomic reference scale for all measured NMR line shifts in the liquid and solid state and the possibility of comparing experimental and theoretical shielding constants. As a consequence, the amount of the Knight shift of metallic cadmium becomes 20% larger.     

Electromagnetic transition strengths and nuclear moments in123Xe

The level structure of¹²³Xe has been studied with the¹¹⁴Cd (¹²C, 3n) and^?Cd (¹³C, 4n) reactions using in-beamγ-ray spectroscopy. The yrast cascade on the low lying odd parity states originating from theh _11/2 neutron orbital has been investigated yielding lifetimesτ of 18(3) ps, 2.2 (4) ns and 17(2) ns for the 15/2^?, 11/2^? and 9/2^? states, respectively. Theg-factor of thet _1/2=5.2 μs isomer has been measured to beg=?0.256(2). From the time differential observation of the electric quadrupole interaction in a¹¹⁴Cd single crystal the spin of this isomer has been determined to be 7/2 and from the coupling constante ² Qq/h=116(2) MHz the quadrupole moment was deduced. The results are discussed in the framework of the triaxial rotor plus particle model.     

Optical pumping of short lived Β-radioactive isotopes and the magnetic moment of37K

²¹Na (T _1/2=23 sec) and³⁷K(T _1/2=1.25 sec) have been produced in gas targets by (d, n) reactions and polarized by means of optical pumping or spin exchange scattering with optically pumped⁸⁷Rb. An asymmetry up to 3% in theΒ-decay of the polarized nuclei was found, which served to detect rf transitions between hfs levels of the atomic ground states of²¹Na and³⁷K.δF=0 andδF=1 resonances have been recorded, yielding spin, hfs separation and magnetic moment, especiallyI(³⁷K)=3/2,δW(³⁷K)=240.266 (3) Mc/sec andΜ _I(³⁷K)=0.02033(6) nm (diamagnetically corrected). For²¹Na earlier rf-spectroscopic data have been confirmed.     

Orientation of199mHg by optical pumping detected by γ-radiation anisotropy

^199mHg was produced and mass separated at the ISOLDE facility (CERN). Nuclear orientation achieved by optical pumping via the resonance line 6s ^{2 1} S ₀→6s6p ³ P ₁,λ=2537Å was monitored by means of the anisotropy of theγ-radiation emitted in the cascade^199mHg(I=13/2⁺) $${}^{199m}Hg(I = 13/2^ + )\xrightarrow[{M4}]{}{}^{199*}Hg(I = 5/2^ - )\xrightarrow[{E2}]{}{}^{199}Hg(I = 1/2^ - ).$$ ^199*Hg(I=5/2^?)¹⁹⁹Hg(I=1/2^?). Maximum anisotropies of 35% (2,8%) were found in the M4 (E2) transition. A Zeeman scanning of the³ P ₁ state yielded the positions ofF=13/2 and theF=15/2 hfs components relative to the reference isotope²⁰⁴Hg at 15.13 (15) GHz and ?2.86 (15) GHz respectively. Isotopic shift and the quadrupole interaction constant were deduced from these values using the knownA factor.δv ^199m/2O4=v ^2O4?v ^199m=12.20 (16) GHzB=?0.86 (25) GHz. From theB factor the spectroscopic quadrupolment was calculated asQ _s =1.54 (44) barn.     

An investigation of theL 2-L 3 Coster-Kronig transition probability for 63≦Z≦96

Nuclear spin polarization in the 4f ¹⁴6s ^{2 1} S ₀ ground state of¹⁷⁵Lu⁺(I=7/2) ions is achieved by optical pumping with the resonance line (¹ S ₀-¹ P ₁,λ=261.5 nm). Nuclear magnetic resonance of the free ions in He buffer gas yields for the magnetic dipole momentμ(¹⁷⁵Lu)=2.2240(11)μ _n (with diamagnetic correction). This value can be used for a more accurate determination of the magnetic dipole moments of other Lu isotopes from knownA factor ratios. A comparison with nuclear induction measurements in solids results in the chemical shiftsδ(LuB₁₂)=?23(5)·10^?4 andδ(LuSb)= ?31(5)·10^?4.