Stark-Effekt-Untersuchungen der Hyperfeinstruktur der 5s25d2D3/2- und 5s25d2D3/2-Terme im In I-Spektrum

The level-crossing technique with combined electric and magnetic fields was used to investigate the hyperfine structure of the 5s ²5d ² D _3/2- and 5s ²6d ² D _3/2-stedes of the In I-spectrum. From the shifts of the level-crossing signals due to the Stark effect of the electric field the Stark constantsβ of both states were deduced: 5s ²5d ² D _3/2: ¦β¦=0.33(3) Mc/(kV/cm)² 5s ²6d ² D _3/2: ¦β¦=6(1) Mc/(kV/cm)². By theoretical calculations with wave functions of the Coulomb approximation one can show, that the Stark effect in both states is mainly due to admixtures of the 5s ²6p- resp.5s ²7p-configuration.     

Determination of the 5d6p 3F4-5d2 3F transition probabilities of Ba I

Whether the transitions between 6s5d ³D and 5d6p ³F can be used for laser cooling of barium heavily depends upon the transition probabilities of 5d6p ³F-5d^{2 3}F. Taking the transition 6s5d ³D₃-5d6p ³F⁴ as a scale, the leakage rate of 5d6p ³F₄-5d^{2 3}F was used to evaluate the transition probabilities. 706 nm laser pulses with different durations were applied to a barium atomic beam for 6s5d ³D₃-5d^{2 3}F₄ optical pumping, and the remaining percentages in 6s5d ³D₃ were measured. After exponential fitting, the transition probability of 5d6p ³F₄-5d^{2 3}F_3,4 was determined to be 2.1(4)×10⁴ s^?1, which is in agreement with theoretical calculations using the scaled Thomas-Fermi-Dirac method.     

Stark-Effekt-Untersuchungen in der Hyperfeinstruktur der 3s 2 3d 2 D 5/2- und2 D 3/2-Terme des Al I-Spektrums

The resonance fluorescence of the transitions 3d ² D _5/2,3/2 3p ² P _3/2,1/2 in the Al I-spectrum was observed as a function of a magnetic field. Adding an electric field parallel to the magnetic field the shifts of level crossing signals caused by the Stark effect of the electric field were used to separate overlapping signals of the 3d ² D _5/2- and 3d ² D _3/2-states. The following values of the Stark parametersβ of both states and the hyperfine structure constantsA andB of the 3d ² D _3/2-states were deduced: 3d ² D _3/2∶ ¦A¦=99(1) Me/sec · g_J/0,8,B/A=?0,22(12), ¦β¦=0.45 (8) Mc/sec/(kV/cm)² · g_J,/0.8, A/β< 0 3d²D_5/2∶ ¦β¦=0.16 (4) Mc/sec/(kV/cm)² · g_J/1.2, A/β>0. Some qualitative aspects of interconfiguration mixing in the 3d²D-states are discussed.     

Tensor hyperpolarizability of the 6 s 19 d1D2 barium rydberg state

Tensor polarizability and tensor hyperpolarizability of the 6s19d¹D₂ Rydberg state of Barium were derived from Stark splittings measured by quantum beat spectroscopy. The hyperpolarizability appearing in the fourth order contribution of the perturbation expansion was expressed in spherical tensor form. Using Coulomb approximation numerical values were calculated which are in fair agreement with experimental results.     

On the beauty of the f xyz orbital in T,T d,D2d and D2 symmetries

This paper focuses on the properties of the tesseral harmonic S³ ₂ which describes the f_xyz orbital. In a few symmetry groups: T, T_d, D_2d and D₂ f_xyz is a basis for the total symmetric representation Γ₁ as well as R which denotes a function going into itself under all proper and improper rotations. The f_xyz, tesseral harmonic is also the only function transforming into itself under a cyclic permutation × → y → z → x. This very unique property is discussed in the framework of the Judd-Ofelt theory. It is shown that the absorption or fluorescence intensity of the J = 2 ? J = 0 transitions in Eu³⁺ are concentrated in one, two or three lines with ratios 3; 2:1; 1:1:1 respectively for T, T_d; D_2d and D₂ because the only tesseral harmonic acting in the induced electric-dipole mechanism is S³ ₂ (without J mixing of course). Two notes are added with respect to the f_xyz, properties in applications as lasers and high-temperature superconductors (HTS).     

Polarisationseffekte in der Hyperfeinstruktur von65Cu I, 3d 94s 2 m 2 D

The hyperfinestructure of the transition⁶⁵CuI, 3d ¹⁰4p ² P _3/2—3d ⁹4s ² m ² D _5/2 was investigated by optical interferometric methods. For the hfs-factors the following values were found:A(⁶⁵Cu,m ² D _5/2)=26,79(3) mK andB(⁶⁵Cu,m ² D _5/2)=5,81(10) mK. The core polarization of them ² D-terms and the Sternheimer corrections in the calculation of the quadrupolmoment of copper 65 from theB-factors of the terms 3d ⁹ 4s² m ² D and 3d ¹⁰ 4p ² P _3/2. were discussed.     

Laser-rf double-resonance hyperfine structure measurements of the metastable 3d 4s 1 D 2 state of43Ca

The hyperfine structure of the (3(d 4s)¹ D ₂metastable state of⁴³Ca has been measured using theABMR-LIRF method (atomic beam magnetic resonance, detected by laser induced resonance fluorescence). The measurements yielded for the magnetic dipole and electric quadrupole constantsA=?17.650(2) MHz andB=?4.642(12) MHz, respectively. From the measuredB factor the spectroscopic electric quadrupole moment (uncorrected for shielding effects) has been calculated to beQ(⁴³Ca)=?0.062(12) barn. In addition, isotope shifts in the lines (3d 4s)¹ D ₂(3d 4p)¹ F ₃ ⁰ and (3d 4s)¹ D ₂(4s 5p)¹ p ₁ ⁰ for the stable calcium isotopes have been obtained by high resolution laser spectroscopy.     

Eine Hyperfeinstruktur-Analyse der Grundkonfigurationen 5d 8 6s 2 und 5d 9 6s des Pt-I Spektrums

The hyperfine structure of the ground configurations 5d ⁸ 6s ² and 5d ⁹ 6s of the stable Platin isotopes 194, 195, 196, 198 was analyzed. For the isotope 195 a complete set of the magnetic splitting constantsA is given. TheA constants of the levels 5d ⁸ 6s ^{2 3} P ₁ and¹ D ₂ were determined for the first time. From these data the electronic splitting constants a_{6 s}=l010(10) mK, a_{d 3/2}=57 (6) and a_{d 5/2}=27 (2) mK could be evaluated. The effect of core polarization is discussed and a fieldκ _cp=?5.6(1.0) a.u. per 5d-electron spin is found. Also the isotopic shift is determined and for the mean quadratic nuclear charge radius the valueΒδ <r ²>=0.095 (10) fm² is derived.     

Lifetime measurements of Rydberg states in the 6snd 1 D 2-series of BaI

We have measured the lifetimes of 10 Rydberg states from 6s8d ¹ D ₂ to 6s 17d ¹D₂ in the Ba I spectrum by time-resolved recording of the exponential decay of the resonance fluorescence in an atomic beam. The excitation was performed by use of two pulsed dye lasers simultaneously pumped by one nitrogen laser. The lifetime results differ strongly from Coulomb approximation calculations and show deviations from a(n ^*)³-dependence.     

Radiative lifetimes of 7d, 8d <Superscript>1</Superscript>D<Subscript>2</Subscript> excited states of Hg I

Radiative lifetimes of 7d, 8d ¹ D ₂ excited states of Hg I are measured using pulsed two-photon excitation from the ground [Xe]5d ¹⁰6s ^{2 1} S ₀ mercury state, detecting the decay of the laser-induced fluorescence. The results are compared with theoretical values, obtained by means of a Hartree-Fock single configuration method, taking into account electron configuration interaction. The radiative lifetime value dependence on the effective principal quantum number for the nd ¹ D ₂ series is analyzed and compared with the quantum defect dependence. Received 25 February 2000 and Received in final form 26 July 2000     

Radiative decay and autoionization in the4 D-states of the 3d 94s5s configuration in CuI

The CuI 3d ⁹4s5s ⁴ D-states, which lie above the ionization limit, were populated by stepwise collisional and laser excitation. With respect to their total angular momentum, the⁴ D-states have completely different decay modes. Whereas the lifetimesτ(⁴ D _7/2)=8.2(4)·10^?9s andτ(⁴ D _1/2)=7.9(6)·10^?9 s are determinrd by radiative transitions and were measured by time-resolved spectroscopy, the lifetimesτ(⁴ D _5/2)=1.59(6)·10^?12s andτ(⁴ D _3/2)=1.28(5)·10^?12s are due to autoionization and were deduced from the widths of the excitation signals observed by ion detection.     

Level-Crossing-Experimente zur Untersuchung der Hyperfeinstruktur des 5d 2 D 5/2-Terms im Indium I-Spektrum

The resonance fluorescence of the transition 5d ² D _5/2?5p ² P _3/2 (λ=3256Å) in the In I-spectrum was observed as a function of an external magnetic field. From the level crossing signals the following values of the hyperfine constantsA andB of the 5d ² D _5/2-state were deduced: ¦A¦=148(8) Mc/sec·g _J/1.2 and ¦B/A¦≦0.3. The widths of the signals yielded the mean lifetimet=7.1 (6)·10^?9 sec · 1.2/g _J . From the shifts of the signals caused by a constant electric field parallel to the magnetic field the value of the Stark parameter ¦β¦=0.19(4) Mc/sec/(kV/cm)² ·g _J /1.2 and the sign of the ratioA/β<0 were determined. Calculations with Coulomb wave functions show that the Stark shifts of the electric field are mainly due to admixtures of the 6p ² P _3/2-state.     

Isotope shift and hyperfine structure of the transition5d6s 2 2 D 3/2-5d6s6p 4 F 3/2 of Lu175 and Lu176

Using a tunable single mode dye laser the isotope shift of the 573.7 nm-line between the isotopes Lu¹⁷⁵ and Lu¹⁷⁶ has been determined to be IS(176?175, 573.7 nm)=?394(5) MHz yielding a change of mean square nuclear radii ofδ〈r ²〉=0.022(5) fm². In addition from our measurements the following values of the hyperfine splitting constantsA andB could be deduced Lu¹⁷⁶ 5d6s6p ⁴ F _3/2:A=?651.4(0.3) MHz,B=2,494(4) MHz 5d6s ^{2 2} D _3/2:A=138.0(0.3) MHz,B=2,131(3) MHz Lu¹⁷⁵ 5d6s6p ⁴ F _3/2:A=?924.7(0.5) MHz,B=1,767(4) MHz.     

Level crossing investigations in the 4d 2 D 5/2,3/2-states of the A1 I-spectrum

The level crossing technique with combined electric and magnetic fields was used to investigate the hyperfine structure, the Stark effect, and the mean life time of the 4d ² D _5/2,3/2-states in the Al I-spectrum. The experimental values are discussed in connection with interconfiguration mixing.     

Der Einfluß eines elektrischen Feldes auf Level-Crossings des 6d 2 D 3/2-Zustands im TlI-Spektrum

The influence of an electric field on the energy levels of the 6d²D_3/2-state in the Tl I-spectrum was studied by measuring the shifts of level crossing signals relative to their magnetic field positions. The following values of the magnetic hyperfine constantA and the Stark parameterβ were deduced: ¦A¦=42(2) Mc/sec · g_J/0.8, ¦β¦=0.12(1) Mc/sec/(kV/cm)² · g_J/0.8 and A/β>0. Assuming that the main part of the energy shifts are caused by admixtures of the 7p²P-states the sign of the Stark parameterβ and —from the measured ratio A/β>0 —the sign of theA-factor should be negative. For electric field strength E?30 kV/cm the energy shifts of the 6d²D_3/2state are considerably greater than the hyperfine structure splitting. Therefore the case of decoupled hyperfine structure is considered.     

Fragmented 2d 5/2, 1g 7/2 and 1g 9/2 deep proton-hole states of207TI

The three proton-hole states ?2d_5/2, 1g_7/2 and 1g_9/2 are found to be fragmented as a result of coupling of these states with the 3^?, 5^?, 2⁺, 4⁺ and 6⁺ collective states of²⁰⁸Pb. The excited states in²⁰⁸Pb (t,α) reaction can be quantitatively explained in terms of altered 2d_5/2, 1g_7/2 and 1g_9/2 states with the hole-core coupling model.     

Low pressure broadening and shift of the 2p 53p-2p 56s neon spectral lines

Natural radiative lifetimes in the perturbed 6s n s ¹ D ₂ (n=12?30) sequence of barium have been measured using the PUMOLS (PUlse-MOdulated Laser Spectroscopy) method, which incorporates pulse-modulation of a CW dye-laser beam and delayed coincidence techniques. Principal perturbers are the 5d 7d ³ F ₂ and¹ D ₂ states. Lifetimes were also measured for these shortlived valence states, which through configuration mixing cause drastic decreases in lifetime values in the region of perturbation of the 6s n d ¹ D ₂ sequence. Two-step laser excitation from the ground 6s ^{2 1} S ₀ state via the 6s 6p ¹ P ₁ state was employed. Special care was taken to determine the influence of black-body radiation transitions on the measured lifetimes.     

Hyperfine-structure and isotope-shift measurements in the 6s 5d↔6p 5d transitions of Ba I in the far-red spectral region

Measurements of the hyperfine structures in the 6p5d ¹ D ₂,³ D ₁ and³ F _{2, 3, 4} states of¹³⁵Ba and¹³⁷Ba, and isotope-shifts in several far-red transitions between the 6s 5d and 6p 5d configurations, as well as the transition 6s ^{2 1} S ₀→6s6p ³ P ₁ at 7,911 Å have been performed using high-resolution laser spectroscopy on a collimated atomic beam of natural barium. An analysis of the magnetic-dipole interaction in the 6p 5d configuration using effective one- and two-body hyperfine operators is presented. In particular the contact interaction was studied with respect to the correlation between the two valence electrons. Effects of strong configuration interaction were found. From a King-plot analysis of the isotope shift term- andJ-dependence of the field shift have been evaluated for the transitions between the 6s 5d and 6p 5d configurations. Relativistic Hartree-Fock (RHF) calculations have been performed of electron densities at the nucleus for six different configurations in Ba I and Ba II. The RHF calculations reproduce the experimental King-plot slopes quite well, while the absolute values, of the changes in electron density at the nucleus for the studied transitions, are found to be 9% lower than the results derived from a muonic experiment.     

Hyperfine structure and isotope shifts in the 5d6s2 a2D3/2--5d6s(a3D)6p z4F5/2 ° transition of Hf II

The hyperfine structure and isotope shifts of the transition between the 5d6s² a²D_3/2 ground state and the 5d6s(a³D)6p z⁴F_5/2 ^° excited state of singly ionized hafnium at \lambda=340 nm have been investigated by laser spectroscopy using a radio-frequency quadrupole ion trap. The magnetic dipole coupling constant A and electric quadrupole coupling constant B of the two atomic levels for both stable isotopes ¹⁷⁷Hf and ¹⁷⁹Hf are determined. The changes of mean square nuclear charge radii \delta[ r²] of the stable Hf isotopes and the radioactive isotope ¹⁷²Hf (T_1/2=1.87a) have been extracted from the data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Rumpfpolarisation des 4d 9 5s 22 D-Zustandes von Ag I

The hyperfine structure of the transition Ag I, 4d ⁹ 5s ²² D _3/2-4d ¹⁰5p ² P _1/2, λ=19,372 Å has been investigated by means of a photoelectrically recording Fabry-Pérot interferometer using separated isotopes. Evaluating the hfs-pattern by a digital analysis the following values for the magnetic dipole interaction constants have been obtained: $$A_{3/2}^{(109)} (d^9 5s^2 ) = - 12.11(6)mK; A_{1/2}^{(109)} (d^{10} 5p) = - 6.72(10)mK.$$ Using the knownA-factor of the other level of the configurationd ⁹ s ² and the values of the Ms anomalies of the levelsd ⁹ s ²² D _5/2 andd ¹⁰ s ² S _1/2 together with our result, the influence of the core polarization on theA-factors of the configurationd ⁹ s ² is discussed. Assuming that the used relativistic correction factors are correct, the influence of the core polarization cannot be due only to the unpaireds-electrons of the core, but must be described by the three-parameter hfs-Hamiltonian given by Harvey. Consequences for calculating the quadrupole moments from hfs data are mentioned.