Precision measurement of the energy of the 4d 9 5s 2 2 D 5/2 metastable level in Ag I

The energy of the 4d ⁹ 5s ^{2 2} D _5/2 metastable level in Ag I, which is the upper level of the very narrow 5s ² S _1/2 – 4d ⁹ 5s ^{2 2} D _5/2 two-photon transition at 661.2 nm, has been determined from precision measurements of the wavelengths of the 206.1 nm (5s ² S _1/2 – 6p ² P ₃ ^2/0 ) and 547.5 nm (4d ⁹ 5s ^{2 2} D _5/2 – 6p ² P ₃ ^2/0 ) lines emitted from a hollow-cathode discharge. The measured energy of the 4d ⁹ 5s ^{2 2} D _5/2 level, 30 242.286(7) cm^–1, is combined with the known hyperfine splittings and the estimated¹⁰⁷Ag-¹⁰⁹Ag isotope shift to obtain accurate absolute frequencies for the hyperfine components of the 661.2 nm transition. These results should help in the detection of the narrow 661.2 nm two-photon transition, which has been proposed as a new optical frequency standard.     

On the hyperfine structure in the configuration 5f 3 6d7s 2 of neutral uranium

A Laser Induced Fluorescence experiment in an atomic beam has yielded experimental values of hyperfine structure (hfs) constants A and B for 28 low odd levels and 22 even levels, with an accuracy around 10^–5 cm^–1 for A and 10^–3 cm^–1 for B. A Condon Slater Racah parametric interpretation of the hfs data concerning 22 of these levels, on the basis of the configuration 5f ³ 6d 7s ², has provided values of monoelectronic parametersa _5f ⁰¹ ,a _5f ¹² ,a _6d ⁰¹ ,b _5f ⁰² ,b _6d ⁰² ,b _6d ¹³ . A least square fit calculation has been compared to the values deduced from Dirac-Fock monoelectronic radial integrals. The fit represents 18 A (16 B) values ranging from –0.42 to –2.96 mK (from –41 to 156 mK) with discrepancies less than 0.2 mK (8 mK).     

Hyperfine structure constants and isotope shift of the levels of the configuration 4f 6 5d 6s 2 in Eu I

The hyperfine structure (hfs) and the isotope shift (IS) of transitions between metastable levels of the configuration 4f ⁷ 5d 6s and levels of the configuration 4f ⁶ 5d 6s ² of¹⁵¹Eu and¹⁵³Eu were studied by means of the high resolution laser-atomic-beam technique. New data for the hfs in¹⁵¹Eu and¹⁵³Eu were obtained as well as new and more accurate for the IS between¹⁵¹Eu and¹⁵³Eu. The measured hfs constantsA andB of the 4f ⁶ 5d 6s ² configuration allow to perform a parametric analysis using the Sandars and Beck theory. The value of the Sternheimer correction is also disscused.     

Radiative recombination rates with different statistical distributions

The isotope shift and hyperfine structure in a rhenium hollow cathode discharge was studied for transitions of the type 5d ⁵6s7s 5d ⁵6s6p and 5d ⁵6s6d 5d ⁵6s6p through Doppler-free saturation absorption laserspectroscopy and high resolution interferometry. Taking configuration mixing in the lower levels of 5d ⁵6s6p under consideration, we obtain average configuration isotope shift values for 5d ⁵6s7s of –1760(100) MHz and for 5d ⁵6s6d of –1970(200) MHz. These experimental values compare extremely well with the theoretically predicted configuration isotope shifts in rhenium, based on pseudo-relativistic Hartree-Fock calculations, of –1710 MHz and –1940 MHz, resp. In addition hyperfine structure constants for rhenium levels of 5d ⁵6s6d are reported here for the first time.Research scientist from the University of Istanbul, Turkey     

Laser and radio-frequency spectroscopy of the 5d 36s 2 4 P 3/2,5/2 states in Ta I

The hyperfine structure of the metastable atomic states 5d ³6s ^{2 4} P _3/2 and⁴ P _5/2 in¹⁸¹Ta has been studied using high resolution laser spectroscopy and laser radio-frequency double-resonance methods.     

Hyperfine structure measurements of the metastable (3d 6 4s 2)3 H 4, 5, 6 states of57Fe: Configuration interaction in the hyperfine structure of the iron atom

We report the hyperfine structure (hfs) measurement of the metastable (3d ⁶ 4s ²)a ³ H _{4, 5, 6} states of⁵⁷Fe. The kHz-precision of these experimental results together with the hyperfine structure values of (3d ⁶ 4s ²)a ⁵ D _{1, 2, 3, 4}, (3d ⁷ 4s)a ⁵ F _{2, 3, 4, 5}, and (3d ⁷ 4s)a ³ F _{2, 3, 4}, which were measured earlier, allowed to determine a very detailed set of effective radial parameters describing the hfs of these states, using a new parametrization method. This method treats one- and two-body contributions to the hfs separately. In this way configuration interaction effects in the hfs of the⁵⁷Fe atom can be studied in detail and compared with configuration interaction effects in the fine structure of the same atom.     

Hyperfine structure in the configurations 4f 13 6s6p and 4f 125d6s 2 of TmI

The laser-atomic-beam spectroscopy has been used to make precise measurements of the hyperfine structure in transitions starting from metastable states of the configuration 4f ¹²5d6s ² in¹⁶⁹TmI. With the resulting experimental magnetic dipole hyperfine constantsA _J andA _J values from former investigations a parametric analysis of the hyperfine structure in the configurations 4f ¹³6s6p and 4f ¹²5d6s ² has been performed using wavefunctions from fine structure calculations. A comparison of theoretical and experimental hyperfine constants allowed a test of the reliability of the wave-functions used. The hyperfine parameters respectively hyperfine radial integrals determined from the analysis were compared with corresponding data from ab initio calculations for the ground configuration in TmI.     

Hyperfine structure investigations in excitedD-states of171Yb and173Yb

The hyperfine structure splittings in the excited 4f ¹⁴6s6d states of¹⁷¹Yb and¹⁷³Yb have been measured. Isotope selection was achieved by stepwise laser excitation of the¹ D ₂ and³ D _{2, 1} states. The³ D ₃ state of¹⁷¹Yb was excited via collisional excitation of an intermediate level. The magnetic and electric hfs coupling constants are given and compared to ab initio values calculated from relativistic self-consistent-field wavefunctions.     

Study of the hyperfine structure of Titanium atom by laser induced fluorescence on an atomic beam

Within the framework of systematic hyperfine structure (hfs) investigation of titanium atom the hfs splitting of 3d ³4s ³H_4,5,6 levels for two stable isotopes ⁴⁷Ti and ⁴⁹Ti have been measured by laser induced fluorescence. Experimental hfs constants A _exp and B _exp have been determined. The hfs measurements confirm an existence of a significant spin-dependent interaction effect on hfs structure of the level 3d ³ 4s ³H₄.     

Sternheimer free determination of the51V nuclear quadrupole moment from hyperfine structure measurements

The hyperfine structure (hfs) of 18 metastable states of⁵¹V has been measured by laser induced fluorescence. 15 of these states have been measured additionally very precisely by the ABMR-LIRF method. Using results of earlier hfs measurements, the hfs of altogether 33 fine structure states is analyzed using a method of simultaneous parametrization of one- and two-body interactions in the atomic hfs of the model space 3d ^{3 +M} 4s ^{2 ?M} (M = 0, 1, 2). The hfs of these states is described by 16 parameters for the magnetic dipole interaction and 12 parameters for the electric quadrupole interaction. From these model space parameters corresponding configuration dependent parameters for the three configurations were determined. These parameters allow a prediction of the hfs constants of all states of the modelspace within an accuracy of 5 to 10%. The evaluation of the nuclear quadrupole moment of⁵¹V, free of Sternheimer corrections up to second order, yielded the value of -0.043(5) barn.     

Hyperfine structure measurements of103Rh

Hyperfine structure has been measured in 28 states of¹⁰³Rh below 34,000 cm^?1. The magnetic dipole interactionA constants in the metastable states 4d ⁸ 5s ⁴ P _5/2,3/2,² P _3/2,1/2,² D _5/2,3/2,² G _9/2,7/2 and 4d ⁷ 5s ^{2 4} F _{9/2,7/2,5/2,3/2} have been determined using the laser radio-frequency double-resonance method and in the states 4d ⁸ 5p ⁴ D _{7/2,5/2,3/2,1/2},⁴ G _7/2,5/2,⁴ F _{9/2,7/2,5/2,3/2},² G _9/2,7/2,² F _7/2,5/2 and² D _5/2,3/2 by high-resolution laser spectroscopy.     

Collision energy dependence of He and Ne capture by C 60 +

The hyperfine structure and the isotope shifts in the optical transition of HfI with λ=5903 Å have been investigated using high resolution laser spectroscopy. The magnetic dipole and electric quadrupole hyperfine splitting constants of the lower 5d ² 6s ² a ³ F ₃ and upper 5d ² 6s 6p z ⁵ G ₃ ⁰ levels have been determined for the two stable odd hafnium isotopes¹⁷⁷Hf and¹⁷⁹Hf.     

Hyperfine structure in 5s 4d 3 D —5snf transitions of87Sr

The hyperfine spectra of the 5s4d ³ D ₁-5s20f, 5s4d ³ D ₂-5s23f, and 5s 4d ³ D ₃-5s32f transitions of⁸⁷Sr (I=9/2) have been measured by collinear fast beam laser spectroscopy. The structure in the upper configurations is highly perturbed by fine structure splitting that is of comparable size to the hyperfine interaction energy. These perturbations can be adequately treated with conventional matrix diagonalization methods, using the 5s-electron magnetic dipole interaction terma _5s and the unperturbed fine structure splittings as input parameters. Additionally, hyperfine constants for the lower 5s4d ³ D configurations, including theA- andB-factors and a separation of the individuals- andd-electron contributions to these factors, are derived.     

Isotope shifts and hyperfine structures investigation of doubly excited levels in SrI

We measured isotope shifts and hyperfine structure of visible transitions of stable strontium isotopes by means of Doppler-free saturated absorption spectroscopy. In particular, we investigated transitions between excited states where the upper level involves two excited electrons. We report hyperfine coupling constants for the levels 5p4d¹D₂, 5p4d³F₂, 5s4d³D₁, 5s6s³S₁, 5s5p³P₁ and, for some of the studied transitions, we separate the specific mass and volume contribution to the isotope shifts.     

Experimental and theoretical study of the hyperfine structure in the (5d+6s)96p configurations of Pt I

The hyperfine structure of the odd configurations 5d ⁹6p and 5d ⁸6s6p was studied with laser optogalvanic spectroscopy and high resolution interferometry in a platinum hollow cathode. A parametric hyperfine structure analysis for the configurations (5d+6s)⁹6p with 10 excited odd-parity levels was performed for¹⁹⁵Pt. We obtained one-electron hfs parameters,a _5d ⁰¹ =1160(320) MHz,a _6s ¹⁰ =35600(5300) MHz anda _6p ⁰¹ =1300(780) MHz for the configuration 5d ⁸6s6p. The corresponding $\left\langle {r^{ - 3} } \right\rangle _{nl}^{k_s k_l } $ values are compared with those known for other 5d-elements.     

Hyperfine structure investigation on the (3d 4)3 G 4,5 levels of47Ti

Using two-step laser spectroscopy with the sideband technique the hyperfine structure (hfs) splittings of the levels (3d ⁴)³ G _4,5 in⁴⁷Ti have been measured. These are the first hfs measurements of the levels belonging to the 3d ^N+2 configuration of the system (3d+4s) ^N+2. The experimental results indicate a strong increase of the core polarization effect due to excitation of both 4s-electrons to the open 3d-shell.     

Scalar and quadrupolar intensity contributions in two-photon hyperfine structure transitions in europium

Two-photon transitions from the Eu I ground state 4f ⁷ 6s ² a ⁸ S _7/2 to odd levels with alsoJ=7/2 in the energy range of 34,000 – 36,700 cm^–1 were analysed due to their scalar and quadrupolar contributions. Their ratioR (g, e) were determined experimentally. In most cases the quadrupole contributions are dominant, i.e. 0R (g, e) _exp <>^–3. In the two-photon transition to the level 4f ⁷ 5d ^{2 8} F _7/2 the ratio is remarkably strong:R (g, e) _exp =134 (4)·10^–3. A theoretical estimation ofR (g, e) is not yet satisfying, due to strong configuration mixing in Eu.     

Doppler free “dark resonances” for hyperfine measurements and isotope shifts in Ca+ isotopes in a Paul trap

We have observed dark resonances in theA-type level structure, formed by the 4S_1/2 ground state, the 4P_1/2 excited state and the low lying metastable 3D_3/2 state in the Calcium ion, confined in a Paul radio-frequency trap. These Doppler-free and potentially very narrow resonances were used to determine the magnetic dipole hyperfine interaction constant A for the 4P_1/2 and 3D_3/2 state of⁴³Ca⁺, giving –142(8) MHz and –48.3(1.6) MHz, respectively. From measurements of the P-D (E1) and S-D (E2) transition wavelength in a mixture of⁴³Ca⁺ and⁴⁰Ca⁺ we determined the isotope shifts of these lines.     

Hyperfine structure in the configuration 4f 115d6s 2 of Er I

Hyperfine constants of low lying levels of the configuration 4f ¹¹5d6s ² in Er I have been measured for the only stable odd isotope,¹⁶⁷Er, using high resolution laseratomic-beam spectroscopy. Hyperfine parameters were evaluated from the experimental data using the effective tensor operator formalism. For this purpose eigenfunctions have been determined from an analysis of the fine structure energies of Er I as well as from ab initio multiconfiguration Dirac-Fock calculations. With the latter method also ab initio hyperfine constants for the levels investigated were evaluated. A comparison of calculated fine structure energies, Landég _J -factors and hyperfine constants with the experimental data allowed a test of the reliability of the fine structure and multiconfiguration Dirac-Fock wavefunctions. Effective nuclear electric quadrupole moments for¹⁶⁷Er have been determined from the experimental hyperfine constants using both calculated relativistic electronic radial integrals and hyperfine parameters for the 4f and 5d electrons in the configuration 4f ¹¹5d6s ² in Er I. From a comparison with the nuclear quadrupole moment measured in the mesic atom Sternheimer shielding factors are calculated. Configuration-interaction contributions to the radial integrals 〈r ^?3〉 _nl ⁰¹ of the 4f and 5d electrons have been determined.