Bestimmung der Hyperfeinstrukturaufspaltungen der Scandium-Grundzustände2 D 3/2 und2 D 5/2 und des Quadrupolmomentes des Sc45-Kernes

The hyperfine structure splittings of the electronic ground states² D _3/2 and² D _3/2 of the stable isotope Sc⁴⁵ have been measured by the atomic beam magnetic resonance method. From these splittings the magnetic dipole and electric quadrupole interaction constants are found to bea _3/2=(269,560±0,02) Mc/sb _3/2=?(26,37±0,1) Mc/sa _5/2=(109,034±0,01) Mc/sb _5/2=?(37,31±0,1) Mc/s. The values of the electric quadrupole moment calculated fromb _3/2 andb _5/2 differ by about 5% indicating that the configuration 3d 4s ² of the ground states is perturbed by higher configurations. Averaging these two values we obtain for the quadrupole moment of Sc⁴⁵ Q(Sc⁴⁵)=?(0,22±0,01) · 10^?24 cm².     

Die Hyperfeinstruktur des angeregten 32P3/2-Zustandes von Natrium

The hyperfine structure of the 3²P_3/2-state in the Na(I)-spektrum was investigated by optical double resonance. Three zero fieldrf-transitions (ΔF=±1, Δm_F=0) were detected and thus the unambiguous interpretation of therf-spectrum was made possible. From an analysis of therf-spectrum one obtains the magnetic hyperfine structure splitting constant a=(18.5 _?0.2 ^+0.6 ) Mc/sec the electric quadrupole interaction constantb=(3.2±0.5) Mc/sec which yields an electric quadrupole moment Q(Na²³)=(0.138±0.025)·10²⁴cm².     

Messung der Hyperfeinstrukturaufspaltung des4F9/2-Grundzustandes im Co59-I-Spektrum und Bestimmung des Quadrupolmomentes des Co59-Kernes

The hyperfine structure splittings of the electronic ground statea ⁴ F _9/2 in the Co⁵⁹-I-spectrum have been measured with a magnetic atomic-beam resonance-apparatus. From these splittings the magnetic dipole and electric quadrupole interaction constants are found to beA (a ⁴ F _/2)=(450,284±0,01) Mc/sec,B (a ⁴ F _9/2)= (139,63±0,5) Mc/sec. Taking into account the mixture of thea ⁴ F _9/2 state with states of the same 3d ⁷ 4s ²-electron-configuration, an electric quadrupole moment of Co⁵⁹ ofQ=(0,404±0,04) 10^?24 cm² was obtained. No Sternheimer-correction has been included.     

Bestimmung des elektrischen Kernquadrupolmomentes des ungeraden stabilen Strontium-87-Kerns

In order to determine the electric quadrupole moment of Sr⁸⁷ (I= 9/2) the hyperfine structure-splitting of the 5s5p ³ P ₁-state of the SrI-spectra was investigated by optical double resonance. By detection of high frequency transitions (ΔF=±1,Δm _F=0,±1) in an external magnetic fieldH ₀≈0 one obtains the hyperfine structure separations asv _F=11/2?F=9/2=1463·149 (6) Mc/sec andv _F=9/2?F=7/2=1130·264 (6) Mc/sec. From these frequencies one calculates the magnetic hyperfine structure-splitting constantA=?260·084 (2) Mc/sec and the electric quadrupole interaction constantB=?35·658 (6) Mc/sec. B leads to an electric quadrupole moment ofQ(Sr⁸⁷)=+0·36 (3)·10^?24 cm².     

Bestimmung von Moleküleigenschaften des Tl205F19 aus kombinierten Stark-Zeeman-Effekt-Messungen mit der Molekularstrahlmethode

An electric Molecular-Beam-Resonance-Spectrometer has been used to measure simultanously the Zeeman- and Starkeffect splitting of the hyperfinestructure of TlF. Electric fourpole lenses served as focusing and refocusing fields of the spectrometer. A homogenous magnetic field (Zeeman-Field) was superimposed to the electric field (Stark-Field) in the transition region of the apparatus. The observedΔm _J =±1 -transitions were induced electrically. Completely resolved spectra of Tl²⁰⁵F¹⁹ in theJ=1 rotational, andυ=0 vibrational state have been measured. The obtained quantities are: The rotational magnetic momentμ _J of Tl²⁰⁵F¹⁹ in the stateJ=1,υ=0, and the difference of the magnetic shielding (σ _1,±1?σ _1,0) of both nuclei as well as the difference of the molecular susceptibility (ξ _1,±1?ξ _1,0) in the states (J, m _J)=(1,±1) and (J, m_J)=(1, 0). The sign of the rotational magnetic moment could be determined unambigously by the influence of offdiagonal matrix elements. The numerical values for Tl²⁰⁵F¹⁹ in the stateJ=1 andυ=0 are:μ _J =?29,153(21) · 10^?6 μ _Bohr (σ _1,±1?σ _1,0)^Tl=?0,002291 (33) (σ _1,±1?σ _1,0)^F=?0,000206(9) (ξ _1,±1-ξ _1,0)=+3,02(15) · 10^?30erg/Gauß² The quantities in brackets are root-mean-square deviations in units of the last digit. From these data and the known values for the spin-rotational interaction constants a number of expressions are derived which characterise the electronic charge distribution in the molecule.     

Hyperfine-structure measurements on Dy161 and Dy163

In an atomic beam magnetic resonance experiment the hyperfine interaction constantsA andB of the⁵ I ₈ groundstate of Dy¹⁶¹ and Dy¹⁶³ were found to be Dy¹⁶¹:A=?(115.8±1)MHz, Dy¹⁶³:A=(162.9±0.6)MHz,B=(1102±15)MHz,B=(1150±20)MHz. Using an effective value for 〈r^?3〉, the magnetic moments and electric quadrupole moments of the Dy¹⁶¹ and Dy¹⁶³ nuclei were calculated to be Dy¹⁶¹:μ _I=?(0.47±0.09) n.m., Dy¹⁶³:μ _I=(0.66±0.13)n.m.,Q=(2.36±0.4)barns,Q=(2.46±0.4)barns.     

Studies of characteristic flash X-ray lines

Level crossings obeying the selection ruleΔm=2 have been detected in the 6² P _3/2-state of both Rb⁸⁵ and Rb⁸⁷. Using the measured crossing points, the ratios of the hyperfinestructure constants to theg _J -factor are determined from a calculation for intermediate magnetic fields. The ratios areA ₈₅/g _J =6.119 (3) Mc/s,B ₈₅/g _J =6.14 (2) Mc/s,A ₈₇/g _J =20.70 (3) Mc/s,B ₈₇/g _J =2.93 (5) Mc/s. From the zero field level crossing of Rb⁸⁷ the lifetimeτ=1.14 (6) · 10^?7sec of the 6²P_3/2-state is obtained. Level crossing signals have also been observed in the presence of noble gas admixtures.     

Messung der Lebensdauer angeregter Kernniveaus von Al28, Cs133, Pr141, W182 und Pt195

The halflife of excited states in some nuclei has been measured by the method of delayed coincidences. Two different experimental arrangements have been used: a conventional scintillation counter equipment and a fast gasfilled parallelplate avalanche-counter. The results of these measurements are: 31 keV-level in Al²⁸:T _1/2=(1.91±0.08) · 10^?9 sec, 81 keV-level in Cs¹³³:T _1/2=(6.25±0.05) · 10^?9 sec, 145 keV-level in Pr¹⁴¹:T _1/2=(1.85±0.03) · 10^?9 sec, 100keV-level in W¹⁸²:T _1/2=(1.45±0.04) · 10^?9 sec, 1290 keV-level in W¹⁸² T _1/2=(1.05±0.03) · 10^?9 sec, 99 keV-level in Pt¹⁹⁵:T _1/2≦1.6 · 10^?10 sec, 129 keV-level in Pt¹⁹⁵:T _1/2=(6.2±0.7) · 10^?10 sec. These experimental values are discussed and compared with theoretical model predictions.     

Die Hyperfeinstrukturaufspaltung des Grundzustandes2 S 1/2 und das magnetische Kerndipolmoment von Au197

The hyperfine structure of the groundstate 6s ² S _1/2 and the nuclear magnetic dipole moment of gold 197 have been studied by the atomic beam magnetic resonance technique. A special high frequency arrangement is described. The hyperfine structure separationΔ v was determined fromΔF=1 transitions. The magnetic dipole momentμ _I was measured by a direct method. The experiments yield the following results:Δv (²S_1/2)=(6099,309±0,010) Mc/secμ _I (Au¹⁹⁷)=+(0,1445±0,0014)μ _K.     

Messung der Lebensdauer angeregter Kernniveaus von Gd155

Using two different experimental arrangements, the halflife of the following excited nuclear states in Gd¹⁵⁵ have been measured by the method of delayed coincidences: 60.0 keV-level:T _1/2=(2.4±0.6) · 10^?10 sec, 86.5 keV-level:T _1/2=(6.35±0.09) · 10^?9 sec, 105.3 keV-level:T _1/2=(1.14±0.03) · 10^?9 sec. These results are discussed and compared with the predictions of the collective model.     

Level-crossing-Untersuchung der Hyperfeinstruktur des 3d 10 4p 2 P 3/2-Terms von Cu63 und Cu65

The level-crossing technic has been used to investigate the hyperfinestructur of the 3d ¹⁰ 4p ² P _3/2-term in Copper I by scattering the resonance line λ=3248 Å on an atomic beam of separated isotop Cu⁶³ respectively Cu⁶⁵ in an external magnetic field. From the level-crossing signals values for the magnetic dipol interaction constantsA and for the electric quadrupol interaction constantsB are deduced to beeA(Cu⁶³)=(194,72±0,15) Mc/secB(Cu⁶³)=?(28,8±0,6) Mc/secA(Cu⁶⁵)=(208,57±0,15) Mc/secB(Cu⁶⁵)=?(25,9±0,6) Mc/sec. With theA-value of the 3d ¹⁰ 4p²P_1/2-term from optical measurements the ratioA(² P _3/2)∶A(² P _1/2)≈0,4 is about twice greater than for an unperturbetalkali-like²P-term. From the width of the level-crossing signals a mean lifetime of the 3d¹⁰ 4p²P_3/2-term τ=(7,0±0,2) · 10^?9 sec is deduced.     

Spins und γ-Multipolordnungen beim Zerfall Fe59→Co59

In the decay of Fe⁵⁹ the following quantities have been measured:γ-ray intensities, conversion coefficients andβ-(circularly polarizedγ) correlations. The conversion coefficients were found to be: for the 1.10 MeVγ-transition, α_tot.=(1.36±0.10)·10^?4 and for the 1.29 MeVγ-transition, α_tot.=(1.07±0.08)·10^?4. The asymmetry parameterA of the correlationβ(0.27 MeV)?γ(1.29 MeV) were measured to beA= ?0.17±0.10, and forβ(0.46 MeV)?γ(1.10 MeV),A=?0.13±0.04. From these data and publishedγ?γ angular correlation measurements the following spins of Co⁵⁹ levels could be deduced: 1.10 MeV,I=5/2^?; 1.29 MeV,I=5/2^?; and 1.43 MeV,I=3/2^?. The two strongβ-ray groups are pure Gamow-Teller transitions (ΔI=1). The multipolarities of all fiveγ-rays are given.     

Derg R -Faktor des 2+-Rotationsniveaus von Er168

The rotation of the angular correlation between theγ-group at about 820 keV and the 80 keV radiation in the decay of Tm¹⁶⁸ has been observed in an external magnetic field of 20300 gauss. The result:ω _R·τ=0,485±0,051 yields for theg _R -factor of the 80 keV state of Er¹⁶⁸:g _R =+0,25±0,03. The evaluation includes a paramagnetic correction factor of:β=7,26, (B _eff=β·B _ext). The angular correlation is slightly attenuated by internal fields. For a liquid source of Tm (NO₃)₃ solved in 3 n HNO₃, a measurement of the differential angular correlation as a function of the delay time gave:λ ₂=(5,8±2,9)·10⁷sec^?1, assumingA ₂(t)=A ₂(0)·e ^?λ ₂·t. The half life of the 80 keV state was found to be:T _1/2=(1,92±0,04)·10^?9sec in agreement with earlier measurements.     

Zur Hyperfeinstruktur des 62P3/2-Terms von Rb87

The hyperfine structure of the 6² P _3/2 state of Rb⁸⁷ has been reinvestigated with optical double resonance in zero magnetic field. The results for the hfs-splitting constants areA(6² P _3/2, Rb⁸⁷)=27.70 (2) Mc/s andB(6² P _3/2, Rb⁸⁷)=3.94 (4) Mc/s. From these constants one obtains a value for the nuclear quadrupole moment uncorrected for shielding effects ofQ=+0.138 (1)·10^?24 cm².     

Bestimmung der Kernmomente des Ho165 aus der Hyperfeinstruktur des Grundzustandes im Ho I-Spektrum

In an atomic beam magnetic resonance experiment, the hyperfine interaction constantsA andB of the⁴ I _2/15-groundstate of Ho¹⁶⁵ were found to beA=800,58389 (50) MHz,B=?1667,997 (50) MHz. Using an effective value for 〈r ^?3〉, the magnetic moment of the Ho¹⁶⁵ nucleus was calculated to beμ=4·1(4)μ _n . The quadrupolement was determined by use of the 〈r ^?3〉 given byWatson andFreeman. The result isQ=2·4·10^?24 cm².     

Messungen derK-Konversionskoeffizienten und der Aktivierungsquerschnitte der isomeren Atomkerne Se77m,Se79m,Ge75m und Ge77m

TheK-conversion coefficients α _K of the nuclear isomers Se^77m , Se^79m , Ge^75m and Ge^77m have been measured by detecting theK-röntgen- andγ-radiation from neutron-irradiated Se- and GeO₂-samples with the aid of scintillation counters to be α _K =0.79±0.06, 7.4±0.6, 1.44±0.13, and 1.2±0.6, respectively. In all cases, the values obtained, are in agreement with those taken from the tables ofRose under the assumption of anE3-transition, thus confirming this assignment which was proposed earlier by other authors. In addition, the cross sectionsσ for inducing the activities by slowed down neutrons have been measured to beσ=22±2, 0.40±0.04, 0.20±0.02, and 0.12±0.03 barns, respectively, and are compared with earlier data of several authors.     

Kern-Isomerie bei In116

The short lived indium isomer produced by thermal neutron capture is confirmed to be In¹¹⁶. A new determination of half-live andγ energy yieldsT _1/2=(2.17α0.07) sec andE _γ=(164±1) keV. From measurement of theK shell conversion coefficient follows that the multipolarity of the transition isE 3, leading to a spin and parity assignment of 8^? for the isomeric level.     

Die Konversion des Hg199m

Hg^199m was produced from natural HgO by fastn irradiation. The cascade decay was investigated with scintillation spectrometers by application of the summing technique. The following results were obtained: half-lifeT _1/2=(43±0,5) min; energy of the isomeric transitionE _γ1=(375±3)keV; conversion coefficients α _K375=3,05±0,25; α_total=5,45±0,25; yielding the multipole order of the isomeric transition to beM4+(25±15)%E5; energy of the second transitionE _γ2=(159±2)keV; conversion coefficients α _K159=0,30±0,03; α_total=0,9±0,1, confirming the multipolarityE2 of this transition.     

Gleichzeitige Messung von Hyperfeinstruktur,Starkeffekt und Zeemaneffekt des85Rb19F mit einer Molekülstrahl-Resonanzapparatur

A molecular beam resonance apparatus with electric quadrupole lenses asA- andB-fields and with superimposed parallel electric and magnetic transition-fields was used. Molecules in different rotational statesJ, m _J are separated by theA-field. Spectra of molecules in different vibrational states are resolved by their different Starkeffect energies. By this means the following electric and magnetic properties of the molecule could be measured in the rotational stateJ=1 and vibrational statesv=0 and 1: The magnetic and electric dipole moment of the molecule, the scalar and the tensor nuclear dipole — dipole interactiond _s andd _T, the nuclear spinrotational interactionc _F andc _Rb, the nuclear quadrupole interactioneqQ, the nuclear magnetic moment μ_Rb, the anisotropy of the diamagnetic susceptibility ξ_⊥?ξ_∥, the anisotropy of the diamagnetic shielding of the external field by the electrons at the position of the nuclei σ_⊥?σ_∥. Using these quantities it was possible to calculate the quadrupole moment and a weighted quadrupole moment of the electronic charge distribution. The results are: (J=1,v=0) μ_el=8,5464 (17) debμ _J/J=?29,79(2)x10^?6 μ _B d _s/h=0,36(23) kHzd _T/h=0,69(22)kHzc _F/h=10,42(70) kHzc _Rb/h=0,479 (48) kHz.eqQ _Rb/h=?70,3410(26) MHzμ(1?σ_S)Rb=1,3474(5) μ_k (ξ⊥-ξ _∥)=12(6)×10^?30 erg/Gauß² (σ_⊥-σ∥)_Rb=?3,8(2,1)×10^?4 (σ⊥-σ _∥)_F=?2,6(3)×10^?4     

Präzisionsmessung der Hyperfeinstruktur des 52P3/2-Terms und des 62P3/2-Terms von Rb85 und Rb87

To study the modification of the value of the nuclear quadrupole moment obtained without Sternheimer correction from measurements in states with different principal quantum numbers, the hyperfine structure splitting of the 5² P _3/2 and the 6² P _3/2 excited states of Rb I has been investigated with the optical double resonance method. The experiments, in which isotopic enriched samples of Rb⁸⁵ and Rb⁸⁷ were used, have been carried out in the 5² P _3/2 state without a static magnetic field. In the 6² P _3/2 state, a static magnetic field was applied. For the 5² P _3/2 state, the hyperfine structure constants areA(Rb⁸⁵)=25.029(16) Mc/s,B(Rb⁸⁵)=26.032(70) Mc/s,A(Rb⁸⁷)=84.852(30) Mc/s,B(Rb⁸⁷)=12.611(70) Mc/s. The corresponding constants for the 6² P _3/2 state areA(Rb⁸⁵)=8.25(10) Mc/s,B(Rb⁸⁵)=8.16(20) Mc/s,A(Rb⁸⁷)=27.96(35) Mc/s,B(Rb⁸⁷)=3.95(10) Mc/s. The values of the nuclear quadrupole moments, derived from both finestructure states, can be brought into agreement when the Sternheimer core correction is applied. The Landé factor for the 6² P _3/2 state isg _j=1.334(1).