Hyperfine structure studies of Tantalum

A narrow bandwidth ring dye laser pumped by an argon ion laser has been used to investigate the hyperfine structure of the even and odd parity levels of tantalum by optogalvanic spectroscopy in the wavelength range 5640 to 6050 Å. Seventeen transitions have been observed and eight of these have not been reported in the literature so far. These transitions involve 27 levels with 15 odd and 12 even parity configurations. The magnetic dipole hyperfine interaction constants A and the electric quadrupole interaction constants B for these levels have been computed and compared with the data available in literature. The results for the levels at 34799.71 cm^?1, 26960.46 cm^?1 and 19657.78 cm^?1 are reported for the first time.     

Test of advanced hyperfine structure theory by precision radio-frequency and laser spectroscopy in molybdenum

The hyperfine structure splittings of 32 even parity states and of 26 odd partity states of molybdenum have been measured by atomic beam magnetic resonance and by laser induced fluorescence. The analysis of the hyperfine structure data of the even parity configurations (4d+5s)⁶ yields experimental evidence for second order hyperfine interactions. In addition, theg _J factors of 19 fine structure levels have been determined in order to test the quality of intermediate coupling wave functions for the (4d+5s)⁶ configurations.     

The hyperfine structure of the predissociated stateB′0+ of IBr

TheB′0⁺ state of IBr is strongly predissociated which leads to fragmentary rovibrational structure and level broadening. Using Doppler free laser polarization spectroscopy, the hyperfine structure of the sharpest rotational lines of several band fragments in theB′?X system was investigated for the first time. The hyperfine analysis yields a strong vibrational dependence of the nuclear quadrupole interaction for Br and the nuclear spin-rotation interaction for I and Br. The magnitude of the hyperfine parameters and their variation with vibrational state are discussed in a configuration model for the bound and repulsive states according to the observed predissociation.     

The hyperfine structure in the configuration 4f 135d6s6p in ytterbium

Using Doppler-reduced laser induced fluorescence spectroscopy in an atomic beam, the hyperfine structure of 22 levels of the configuration 4f ¹³5d6s6p in neutral ytterbium has been investigated for the two odd isotopes ¹⁷¹ Yb and ¹⁷¹ Yb. The experimental results have been used in a study of the hyperfine structure in regard to a determination of the one-electron parameters for the magnetic dipole and the electric quadrupole hyperfine coupling of the isotope ¹⁷³ Yb in part II of this work.     

Predissociation and hyperfine structure of the B3Πou+ state of Br2

Using molecular-beam laser spectroscopy, the hyperfine structure of the B-X system of ⁷⁹Br₂ was measured to obtain reliable data on hyperfine and rotational predissociation for the levels B(0_u⁺) ν = 11, 13 and 16. We report the first measurement of the hyperfine predissociation with no rotational predissociation on P(1) transitions. The unexpected strongly J-dependent variation of the predissociation parameters leads to the conclusion that the familiar theory describing all known data for the B state of iodine may be inadequate for bromine.     

Stark effect of hyperfine levels of the configuration 4f 7 (8 S) 6s6p in the europium I spectrum

The quadratic Stark effect in the hyperfine structure of all levels of the configuration 4f ⁷(⁸ S)6s6p in europium I, which can be excited by electric dipole radiation from the ground state, has been investigated by laser-atomic-beam spectroscopy. From the measured shifts and splittings of the hyperfine components the scalar and tensor polarizabilities have been deduced. From the polarizabilities radial integrals for electric dipole radiation were determined by a parametric analysis. With these radial integrals theoretical values of the polarizabilities were calculated.     

Rotational and hyperfine parameters of NH2(X2B1) from LMR spectra

Seventeen rotational transitions up to N=7 of the NH₂ radical in its ground vibronic state have been measured by far infrared laser magnetic resonance spectroscopy. Analysis of the Zeeman patterns and hyperfine structure yields precise rotational, spin-rotational and distortion parameters, and isotropic and anisotropic hyperfine interaction parameters for both ¹⁴N and ¹H nuclei.     

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.     

Isotope shift and hyperfine structure of stable platinum isotopes

Isotope shift (IS) and hyperfine structure (hfs) measurements have been performed on seven lines of the platinum I spectrum with interference as well as laser fluorescence spectroscopy. In the latter case a frequency-doubled single-mode cw dye laser was applied. The IS of¹⁹⁰Pt with a natural abundance of only 0.01% was determined to beδν ^{190, 192}=?38.65(8) mK in theλ306.47 nm transition. The IS parameters and the effective hfs integrals in the configuration (5d+6s)¹⁰ were determined in intermediate coupling by a least squares fit of the IS and hfs data with eigenvectors obtained from the platinum fine structure (fs). The results are compared with theoretical values and yield improvedδ〈r ²〉 data.     

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.     

Accurate time-resolved laser spectroscopy on silver atoms

The lifetimes of the silver 5p ² P states have been measured with high accuracy by time-resolved laser spectroscopy using the delayed coincidence technique. Also, the hyperfine structure of¹⁰⁷Ag and¹⁰⁹Ag in these two states has been studied by observing quantum beats.     

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.     

On the hyperfine structure and isotope shift of radium

The hyperfine structure and isotope shift of the heaviest known alkaline earth element radium (Z=88) have been studied in both the atomic Ra I and ionic Ra II spectra. The measurements, carried out by on-line collinear fast-beam laser spectroscopy, yield the hyperfine constantsA andB of the 7s and 7p _1/2 states in Ra II, of all states of the excited 7s 7p configuration and the 7s 7d ³ D ₃ state in Ra I. The data allow a consistent evaluation of the nuclear moments for eight odd-A radium isotopes. In particular, a complete analysis of the hyperfine structure of thesp configuration in the two-electron system provides a stringent test of the validity of the semi-empirical modified Breit-Wills theory. It is shown that the effective operator formalism is equivalent, if relativistic correction functions are used to reduce the number of parameters. The semi-empirical hyperfine fields are evaluated and found to agree generally with those from ab-initio calculations. The isotope shifts in thes?p,s ²?sp,sp?sd transitions are analysed semi-empirically and compared with ab-initio calculations. The consistency of the different analyses proves their validity and classifies the spectrum of Ra I as a model case for a simple and clean two-electron spectrum.     

Polarization spectroscopy of Sr79Br and Sr81Br: Analysis of theX 2 Σ + andB 2 Σ + hyperfine structure

Microwave optical polarization spectroscopy has been used to measure the hyperfine structure in theX ² Σ ⁺ (v=0) electronic ground state of Sr⁷⁹Br and Sr⁸¹Br. Optical hyperfine structure in theB ² Σ ⁺?X ² Σ ⁺ (0,0) system was resolved by Doppler-free laser polarization spectroscopy. The magnetic hyperfine parametersb andc and the electricquadrupole hfs parametereqQ were determined for theX ² Σ ⁺ andB ² Σ ⁺ states of both molecules. The magnetic hfs has been interpreted as an effect of halide electron spin polarization. The electric quadrupole coupling constants are compared with the alkali halides and discussed in terms of Sternheimer antishielding in polar molecules.     

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.     

Reanalysis of the Am I level spectrum and the nuclear quadrupole moments of Am-isotopes

The fine structure (fs) and hyperfine structure (hfs) level scheme of Am I is reanalysed using a semi empirical fitting procedure which incorporates experimental data. Especially new laserspectroscopic measurements of the hfs of some electronic transitions in the Am atom enables us to make a more detailed analysis of 5f ⁷ 7s 7p fine structure in Am I. In particular a relation is given between theB-factor values and the value of the nuclear electric quadrupole moment of²⁴¹Am independent of a calibration by results of nuclear spectroscopy.     

Hyperfine structure of Mn II by fast ion beam-laser spectroscopy

We report the first measurements of the hyperfine splitting of the fine structure levels 3d ⁵'4s a ⁵ S ₂ and 3d ⁵ 4p z ⁵ P _1,2,3 ⁰ in singly ionised manganese in a collinear fast ion beam-laser experiment. The ions are excited by the intracavity frequency doubled output of a ring dye laser. The observed linewidth is sufficiently narrow to identify all hyperfine components of each fine structure level.     

Hyperfine structure constants of the CaII states 4s 2 S 1/2 and 4p 2 P 1/2, 3/2 and the nuclear quadrupole moment of43Ca

The hyperfine structure splittings of the 4s ² S _1/2 → 4p ² P _{1/2, 3/2} transitions in⁴³CaII have been measured by fast ion beam collinear laser spectroscopy. The resonant laser interaction was observed using non-optical detection based on optical ground state depopulation pumping, state selective neutralization and charge state separated particle counting. The extracted magnetic dipole hyperfine structure constants for⁴³CaA(² S _1/2)=?805(2) MHz,A(² P _1/2)=?145.5(1.0) MHz andA(² P _3/2)=?31.9(0.2) MHz are in excellent agreement with relativistic many body perturbation theory predictions available for this alkali-like ion. The combined results are used to evaluate the semi-empirical analysis method. From the electrical quadrupole hyperfine structure constantB(² P _3/2)=?6.7(1.4) MHz and the calculatedB/Q value for this one valence electron configuration, the nuclear quadrupole momentQ(⁴³Ca)=?0.043(9)b is derived. This result supports a previous evaluation based on the hyperfine structure of the two valence electron³ P configurations of CaI.     

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.