Zur Rumpfpolarisation des Rb-Atoms: Hyperfeinstruktur des 72 P 1/2-Terms von Rb85

The hyperfine structure splitting of the 7² P _1/2 state of Rb⁸⁵ has been investigated with optical double resonance spectroscopy. The results are:v _F=3?F=2=52.95(6) Mc/s,A _J=1/2=17.65(2) Mc/s,g _J (7² P _1/2, Rb)=0.6668(1). From the hfs interaction constants of the 7² P multiplett a 12% core polarization contribution to the magnetic hfs of the 7² P _3/2 state can be deduced. Comparison is made between the values of 〈r ^?3〉 calculated from either the magnetic hfs or the² P fine structure separation.     

Determination of theg j -factor in the72 P 3/2-state of133Cs by optical double resonance in a strong magnetic field

The hfs in the 7² P _3/2-state of¹³³Cs has been investigated by optical double resonance in a strong magnetic field. From the positions of the magnetic dipole transitions Δm _j =± 1, Δm _i =0 the magnetic hfs coupling con slanta (7² P _3/2)=16.591(25) MHz and theg _j -factorg _j (7² P _3/2)=1.33410(15) could be derived. Contrarily to recent measurements,g _j agrees well with the value calculated from the Lande formula.     

Die elektrischen Kernquadrupolmomente von Cäsium 131 und Cäsium 132 aus Doppelresonanzmessungen am 72 P 3/2-Term

The hyperfine splitting of the 7² P _3/2-state of the radioactive isotopes¹³¹Cs and¹³²Cs has been investigated by optical double resonance. The hyperfine interaction constants deduced from the measured hfs transition frequencies are¹³¹Cs¹³²CsA(7² P _3/2)+31.73(6) MHz +25.03(12) MHzB(7² P _3/2)?28.63(35) MHz + 23.60(60) MHz These values yield spectroscopic nuclear quadrupole momentsQ _s (corrected for the Sternheimer effect) ofQ _s (¹³¹Cs)=?0.57(1) barnQ _s (¹³²Cs)=+0.47(1) barn. The magnetic interaction constantA of¹³²Cs results in a slightly improved precision of the nuclear magnetic dipole momentμ ₁ (¹³²Cs)=+2.22(1)μ _K . The Cesium isotopes have been produced by (d, xn)-reactions on natural Xenon. Total cross sections of the reactions¹³²Xe(d, 2n)¹³²Cs;¹³⁴Xe(d, 4n)¹³²Cs;¹³⁴Xe(d, 2n)¹³⁴Cs;¹³⁶Xe(d, 4n)¹³⁴Cs;¹³⁶Xe(d, 2n)¹³⁶Cs have been measured between 10 and 29 MeV.     

Estimate of the wavelengths for the first and second resonance lines in the francium I spectra

Relativistic self-consistent-field wavefunctions have been used to calculate one-electron eigenvalues for the ground s-state, the first and the second excited p-states of Sr II, Cs I, Ba II, Fr I and Ra II. When knowing the difference between the experimental energies and the theoretical ones for Sr II, Cs I, Ba II and Ra II the wavelengths for the first and second resonance lines in Fr I have been estimated with the following result: λ(7²P_1/2? 7²S_1/2)=812±10) nm λ(7²P_3/2? 7²S_1/2)=719±10) nm λ(8²P_1/2? 7²S_1/2)=433±5) nm λ(8²P_3/2? 7²S_1/2)=423±5) nm     

Fine- and hyperfine structure analysis of the odd configurations in the lead atom

The fine- and hyperfine structure (hfs) analysis, on the basis of available experimental data for the configuration 6s ²6p6d+6s ²6p7s+6s ²6p8s in PbI has been performed. The Slater integrals, spin-orbit parameters and the effective hfs one-electron parameters have been determined. We find an off-diagonal core-polarization effect in the 6p6d+6p7s-space. Using the calculated radial parameters, the values of the quadrupole moment for stable and radioactive Pb-nuclei have been determined from measuredB-factors of the 6p7s ³P₁ state. In addition, a repulsion effect on the hfs sublevels with the same quantum numberF has been investigated.     

Hyperfine shifts for cesium in Argon at high density

An optical pumping experiment was performed to obtain precise hfs shifts for Cs in Argon. The shifts measured include a term quadratic in the densityρ and a large temperature coefficient. The coefficients of the expansionδv/v ₀=a ρ+bρ ₂ area(80 °C)=?29.8(6)x10^?9(Torr^?1(0°C))b(80 °C)=+11(2)x10^?14(Torr^?2(0 °C)). The shift grows more negative with increasing temperature by 0.37 (2)%/°C.     

Hyperfine spectrum of207Bi by absorption spectroscopy: Isotope shift systematics in heavy elements

The hyperfine spectrum of 38?y ²⁰⁷Bi in the 6p ^{3 4} S _3/2?6p ²(³ P ₀)7s ⁴ P _1/2 3,067-Å resonance line was measured by absorption spectroscopy. The²⁰⁷Bi?²⁰⁹Bi isotope shift is 0.0999(20) cm^?1. The relative isotope shifts in bismuth are found to follow the general pattern of the even-neutron number isotopes for the isotones withZ=80, 81, 82 and 87. The magnetic dipole and electric quadrupole hfs interaction constants for²⁰⁷Bi,A(⁴ P _1/2) =0.1630(3) cm^?1 andB(⁴ S _3/2)=?0.016(3) cm^?1, were obtained. Except for the isotope shift, these more precise values are in agreement with our previous results.     

Bestimmung derg J-Faktoren in den Zuständen 62 P 3/2 und 82 P 3/2 von133Cs

The hyperfine structures of the 6² P _3/2- and 8² P _3/2-states of¹³³Cs have been investigated by optical double resonance in a strong magnetic field. The Landé-g-factors and the hfs coupling constants were found to be:g _J(6² P _3/2)=1.3340(3)g _J(8² P _3/2)=1.3342(2)a(6² P _3/2)=50.02(25) MHza(8² P _3/2)=7.644(25) MHz. Contrarily to recent measurements, theg _J-factors agree well with the value calculated from the Landé formula.     

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.     

Laser-induced shifts and splittings of hyperfine structure lines in electron spin resonance spectra of 35Cl atoms

Laser-induced shifts and splittings of the hyperfine structure (hfs) lines in the electron spin resonance (ESR) spectra of ³⁵Cl atoms have been studied using both dressed-atom theory and semiclassical dispersion theory. In resonant cases, the calculated results by the dressed-atom theory of the ac Stark effect indicate that laser-induced hfs ESR shifts of ³⁵Cl atoms in the ground state 3p^{5 2}P⁰ _3/2 can be more than 1 MHz W^?1 cm², and a single ESR hfs line is split into four lines under the action of a laser beam with intensity 10 W cm^?2. In non-resonant cases, the two theories give similar results for the shifts. The laser-induced broadening of the ESR hfs lines is also calculated and is less than the shifts. The laser-induced shifts in ESR can be observable within the resolution of ESR experiments.     

Isotope shift in the resonance lines of131cesium

Reactor produced¹³¹Cs (T _1/2=9.7 d) was used to investigate the isotope shift against the stable nuclide¹³³Cs in the resonance lines of the Cs I spectrum. Special techniques to prepare the hollow cathode and a completely digitalized method of measuring and evaluation of the hyperfine structure made it possible to investigate short-lived isotopes with high accuracy. The following results were obtained:Δv _IS(133?131; 6p ² P _1/2?6s ² S _1/2)=?0,39 (9) mKΔv _IS(133?131; 6p ² P _3/2?6s ² S _1/2)=?0,28 (20) mK.     

Elektrisches Kernquadrupolmoment von Cäsium 134

The hyperfine structure splitting of the 7² P _3/2 state of Cs¹³⁴ has been measured by optical double resonance spectroscopy in zero magnetic field. The following interaction constants have been obtained: Magnetic hfs constantA(7² P _3/2, Cs¹³⁴)=16.851 (16) MHz. Quadrupole coupling constantB(7² P _3/2, Cs¹³⁴)=18.07 (12) MHz. Then the electric quadrupole moment of Cs¹³⁴ can be calculatedQ _hfs(Cs¹³⁴)=+0.436 (3) barn without Sternheimer correction, andQ(Cs¹³⁴)=+0.356(2) barn with Sternheimer correction. A method for the production of alkali resonance cells with quantities of less than 10¹⁴ atoms of the radioactive isotope is described.     

Investigation of the HFS in the 6s6p1P1 state of 173Yb(I) LC and AC spectroscopy

The hfs of the 6¹P₁ state of ¹⁷³Yb has been investigated by level-crossing and anticrossing spectroscopy. From an optimal fit of experimental and calculated signal curves we get the hfs coupling constants: A = 58.45(80) MHz, B = 589.6(13.0) MHz.     

Fine-structure mixing of excited states of cesium atoms upon an impact on the surface of a sapphire single crystal

The spectrum of resonantly excited luminescence of Cs atoms in a microcell with sapphire windows has been studied. Spectral wings of atomic luminescence near the windows have been revealed near (±50 cm^?1) the D2 line of the excited 6S _1/2–6P _3/2 transition. At the same time, the radiation of the D1 line has been found. The features of the spectrum of the far wings, namely, the exponential shape and the relatively small difference between the static and the antistatic wings, as well as the radiation of the D1 line, have been explained by the mixing of fine-structure states due to interactions of Cs atoms with the sapphire windows. From the relative intensity of the lines, it has been determined that the probability of luminescence quenching at the window surfaces differs from unity by no less than 1/700.     

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.     

Hyperfeinstrukturaufspaltung und Lebensdauer des 72 P 3/2-Terms von Rb85 und Rb87

The hyperfine structure splitting of the 7² P _3/2 state of Rb⁸⁵ and Rb⁸⁷ has been measured with optical double resonance. The following hfs interaction constants have been obtained: Rb⁸⁵:A _7p ⁸⁵ =3.71(1) MHz;B _7p ⁸⁵ =3.68 (8)MHz. Rb⁸⁷:A _7p ⁸⁷ =12.57(1) MHz;B _7p ⁸⁷ =1.71 (3)MHz. These values yield quadrupole moments ofQ _7p,hfs ⁸⁵ =+0.316(7) barn andQ _7p,hfs ⁸⁷ =+0.147(2)barn which are reduced by application of the Sternheimer correction toQ _7p ⁸⁵ =+0.267(6) barn andQ _7p ⁸⁷ =+0.124(2) barn. The averaged ratio of the uncorrected values of Q_hfs in the 5p and 7p ² P _3/2 stake isQ _5p,hfs/Q _7p,hfs=1.07(3). This has to be compared with the correction factors for polarization of the core of electrons by the nuclear quadrupole moment (1?R)_5p/(1?R)_7p=1.07. The agreement between the measured and calculated ratio indicates a net antishielding of the nuclear quadrupole moments of rubidium by the core of electrons as has been predicted bySternheimer. The lifetime of the 7² P _3/2 state of the RbI-spectrum is:τ(7² P _3/2, Rb)=2.4(2)·10^?7 sec.     

Partial cross sections for Rb− photodetachment in the region of the Rb(5p 2 P 1/2 3/2) thresholds and their analysis by multichannel quantum defect theory

A crossed ion-laser beam apparatus has been used to measure accurate relative total and partial cross sections for photodetachment from Rb^? ions with high photon energy resolution (0.1–0.6 cm^?1) in the region of the Rb(5p ² P _1/2,3/2) thresholds (photon energy range 16,350–16,820 cm^?1). Satisfactory fits to these data by multichannel quantum defect theory (MQDT) have been obtained, resulting in a reliable set of seven MQDT parameters. The electron angular distribution parameter for the Rb(5_s) channel was found to beβ(5s)=2, independent of photon energy. MQDT predicts a sharp, window-type variation of?(5s) around the minimum of the 5s-cross section below the Rb(5p ² P _1/2) threshold (where an accurate experimental measurement ofβ(5s) was not possible) and a similar behaviour ofβ(6s) in the case of Cs^?photodetachment below the Cs(6p ² P _1/2) threshold.     

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.     

Hyperfine structure,g j factors and lifetimes of excited2 P 1/2 states of Rb

The hyperfine structure of the 6² P _1/2 and 7² P _1/2 state of⁸⁵Rb and⁸⁷Rb and of the 6² P _3/2 state of⁸⁷Rb has been investigated with optical double resonance at intermediate magnetic fields. The magnetic interaction constants,g _j factors and lifetimes are: $$\begin{gathered} 6^2 P_{1/2} state: A\left( {^{85} Rb} \right) = 39.11\left( 3 \right) MHz,A\left( {^{87} Rb} \right) = 132.56 \left( 3 \right)MHz, \hfill \\ g_j = 0.6659\left( 3 \right), \tau = 1.14\left( {13} \right) \cdot 10^{ - 7} \sec , \hfill \\ 7^2 P_{1/2} state: A\left( {^{85} Rb} \right) = 17.68\left( 8 \right)MHz,A\left( {^{87} Rb} \right) = 59.92\left( 9 \right)MHz, \hfill \\ g_j = 0.6655\left( 5 \right), \hfill \\ 6^2 P_{3/2} state: g_j = 1.3337\left( {10} \right), \tau = 1.12\left( 8 \right) \cdot 10^{ - 7} \sec for ^{87} Rb. \hfill \\ \end{gathered} $$ From the hfs coupling constants of then ² P multiplets a 11.5% core polarization contribution to the magnetic hfs of then ² P _3/2 states is obtained, which is found to be independent from the main quantum numbern. The expectation values <r ^?3> _j for thenp valence electrons corrected for core polarization are compared with those derived from the² P fine structure separation. Good agreement is achieved for allnp levels with the choice ofZ _i =Z?3=34 for the effective nuclear charge number. The nuclear quadrupole moments of⁸⁵Rb and⁸⁷Rb are rederived on the basis of this more improved treatment for thep-electron-nucleus interaction yielding $$\begin{gathered} Q_N \left( {^{85} Rb} \right) = + 0.274\left( 2 \right) \cdot 10^{ - 24} cm^2 \hfill \\ Q_N \left( {^{85} Rb} \right) = + 0.132\left( 1 \right) \cdot 10^{ - 24} cm^2 \hfill \\ \end{gathered} $$ where the error does not include the remaining theoretical uncertainty of about 10%.     

Determination of isotope shift crossed-second-order-effects and hyperfine-structure parameters in the Eu I configuration 4f 7 6s7s

In the Eu I configuration 4f ⁷(⁸ S)6s7s the isotope shift (IS) and hyperfine-structure (hfs) of the levelse ⁸ S _7/2 andf ⁸ S _7/2 were determined from the transitions 684.5 nm, 733.7 nm and 821.0 nm to 4f ⁷6s6p. Together with experimental results of our previous measurements a theoretical analysis of the IS and hfs for the complete configuration 4f ⁷ 6s7s can now be carried out. From the IS of the four 6s7s-levels we evaluated the two crossed-second-order-parametersg ₃(4f,6s)= ?l.l(l)mK andg ₃(4f, 7s)= ?0.1(l)mK. The ratiog ₃/G ₃ is determined for various Eu configurations and found to be equal to 5.6(3)·10^?6 in complete agreement with a theoretical value following from Hartree-Fock calculations. The single electron hfs splitting constantsa ¹⁰(4f)= ?1.9 (3) mK,a ¹⁰(6s)=396(3)mK, anda ¹⁰(7s)=65(3)mK are also determined and compared with those of other Eu configurations.