Isotope shift measurements in titanium I

The use of an effusive beam of titanium atoms crossed with a CW single-mode tunable dye laser has allowed the high-resolution, Doppler-free study of the isotope shifts between⁵⁰Ti,⁴⁸Ti and⁴⁶Ti, for seven 3d ² 4s ² a³ F _J 3d ² 4s 4p z ⁵ D _J , visible transitions of Ti I. The measurements show without ambiguity the existence of a non-negligible field shift. Using the values of the nuclear radii of titanium (coming from muonic X-ray measurements), it is possible to determine the respective values of the field and mass shifts.     

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.     

Isotope shift in titanium atom

Isotope shifts in ten optical transitions of Ti atom have been investigated by using laser induced fluorescence on a collimated atomic beam. From the isotope shifts data, using a combined analysis with muonic atom data, specific mass shifts and field shifts have been determined and corrected values of changes of the mean square nuclear charge radii have been obtained.     

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.     

Isotope shift measurements in zirconium by Doppler-free laser polarization spectroscopy

Isotope shifts in 17 transitions of ZrI have been measured by Doppler-free laser polarization spectroscopy in a hollow cathode discharge. The results were combined with other known isotope shift data of ZrI and tested for consistency in a multidimensional King plot. By including values ofδ〈r ²〉 deduced from optical isotope shifts mass and field shifts were separated, and improved values ofδ〈r ²〉 could be determined from the King plot. The results for the isotope pairs A, A′ are as follows; 90, 92: 0.244(43) fm²; 92, 94: 0.176(20) fm²; 94, 96: 0.126(23) fm².     

Investigations of hyperfine structure and isotope shift predictions in Hf II

The fine structure of the even‐parity low configurations of singly ionized hafnium has been reanalyzed by simultaneous parameterization of the one‐ and two‐body interactions for the model space (5d + 6s)³. Using the calculated eigenfunctions, the magnetic‐dipole A hyperfine constants for the whole 37 existing levels of the model space were predicted and compared partially with those obtained using relativistic configuration‐interaction approach. Moreover, combined with experimental data, previously given in the literature, and pseudo‐relativistic Hartree–Fock estimates, the field shifts (FSs) and specific mass shifts (SMSs) of numerous configurations are deduced: FS(5d¹6s²) = 2265 MHz, FS(5d³) = ?1958 MHz, FS(5d¹6p²) = ?1696 MHz, FS(6s²6p¹) = 3135 MHz, and SMS(5d¹6s²) = ?78 MHz, SMS(5d³) = 64 MHz, SMS(6s²6p¹) = ?228 MHz, referred to 5d²6s for the pair ¹⁷⁸Hf–¹⁸⁰Hf. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Semiempirical hyperfine structure and ab initio isotope shift predictions in Zr II

The fine structure of the even‐parity low configurations has been reanalyzed by simultaneous parameterization of the one‐ and two‐body interactions for the model space (4d + 5s)³. Using the calculated eigenfunctions, the magnetic‐dipole A hyperfine constants for the whole 37 existing levels of the model space were predicted and compared partially to those obtained using relativistic configuration‐interaction approach. Moreover, volume shifts (VS) and specific mass shifts (SMS) of numerous configurations of singly ionised zirconium are deduced by means of ab initio estimates combined with a few experimental isotope shift data available in literature: VS(4d¹5s²) = 840 MHz, VS(4d³) = ?649 MHz, VS(4d¹5p²) = ?387 MHz, VS(5s²5p¹) = 1250 MHz, and SMS(4d¹5s²) = ?634 MHz, SMS(4d³) = 484 MHz, SMS(5s²5p¹) = ?1459 MHz, referred to 4d²5s for the pair Zr⁹⁰–Zr⁹². © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Isotope shift in chromium

Thirty-three spectral lines of chromium atom in the blue-violet region (425–465 nm) have been investigated with the method of laser-induced resonance fluorescence on an atomic beam. For all the lines, the isotope shifts for every pair of chromium isotopes have been determined. The lines can be divided into six groups, according to the configuration of the upper and lower levels. Electronic factors of the field shift and the specific mass shift (F_ik and M_ik^SMS, respectively) have been evaluated and the values for each pure configuration involved have been determined. Comparison of the values F_ik and M_ik^SMS to the ab initio calculations results has been performed. The presence of crossed second order (CSO) effects has been observed.     

Isotope effects in electron-donor-acceptor complexes involving aromatic hydrocarbons and fluoranil from NMR shift measurements

Equilibrium constants and NMR shift parameters have been determined for complexes of benzene, toluene and p-xylene and their perdeutero-analogues with fluoranil in cyclohexane solution from NMR shift measurements. Isotope effects are observed in the 1:1 equilibrium constants for the complexes of p-xylene $\text{(}\text{K}{}_1\text{(D)}\text{K}{}_1\text{(H)}$= 1.1₀) and toluene $\text{(}\text{K}{}_1\text{(D)}\text{K}{}_1\text{(H)}$ = 1.0₉). A much smaller effect was observed for the benzene complex which could not be quantified. These results may be interpreted through either the larger electronegativity of H over D, or the greater steric requirements of H over D.     

Optical isotope shifts in titanium I: new measurements

The optical isotope shifts between ⁴⁶Ti, ⁴⁸Ti and ⁵⁰Ti have been measured for eight 3d ³ 4s a ⁵F-3d ² 4s 4p y ³ F lines of titanium by use of a Doppler-free experiment. By contrast with the positive shifts previously measured for 3d ² 4s ² a ³ F-3d ² 4s 4p z ⁵ D lines, these shifts are negative and reveal the presence of large negative specific mass shifts attributed to a d-p electron jump. The interpretation of the present measurements and of former ones is made by means of Hartree-Fock calculations.     

Laser-molecular beam measurement of hyperfine structure in the I2 spectrum

Very high resolution measurements of hyperfine structure on the P(13) and R(15), 43?0, $\text{3}{}_{\mathrm{gp}}{}_0{}^{\mathrm{+}}{}_{\mathrm{u}}\text{←}{}^1\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{+}}$ transitions in iodine 127 were made using laser molecular beam spectroscopy. The observed linewidth was 300 kHz (fwhm) giving a resolution of 5 × 10^?10 The observed spectrum was fitted to obtain a quadrupole coupling strength difference of ΔeQq = 1906 ± 2 MHz and a spin rotation interaction strength difference of ΔC_I = 181 ± 7 kHz between the upper and lower levels of the P(13) transition. For the R (15) transition ΔeQq = 1905 ± 2 MHz and ΔC_I = 167 ± 5 kHz.     

Absorption line narrowing measurements of hyperfine structure in highly excited levels of yttrium

Absorption line narrowing techniques have been used to make original measurements of hyperfine structure in twelve highly excited levels of atomic yttrium. The yttrium vapour, produced by cathodic sputtering in a low pressure, rare-gas discharge, was excited by stepwise excitation with two narrow-band cw lasers. Doppler-free signals have been recorded using both fluorescence and optogalvanic detection. Resonances as narrow as 6 MHz FWHM have been observed in the discharge.     

High precision measurements of hyperfine structures near 790 nm of I 2

High precision measurements of hyperfine splittings of rovibrational lines of the (ν′-ν″)=(0–15) band of the B0 _u ⁺ — X0 _g ⁺ transition of I ₂ were performed in the near infrared around 790 nm using spectrally narrowed diode lasers. Rotational states with J″ between 0 and 99 were investigated and hyperfine parameters could be derived for the two electronic states separately. For the first time the rotational variation of the quadrupole and the spin-rotational hyperfine coupling parameters could be determined for I ₂. A relation is given, by which the hyperfine parameters for a rotational line of the (0–15) band can be predicted, and by which hyperfine splittings of this band can be calculated with an uncertainty of less than 100 kHz for 16 ≤ J″ ≤ 99.     

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.     

Fine structure and hyperfine structure in the excited configuration 5p 26s of the antimony I spectrum

By optical interference and VUV spectroscopy the doublet system of SbI 5p ²6s was investigated, so that now the hyperfinestructure of all 8 levels of 5p ²6s (A- andB-splitting constants) are known. From the analysis we receive a spin-orbit parameter ζ_5p =3,538(57) cm^?1 and from the hyperfine-analysis single electron splitting constantsa _5p ⁰¹ =52.4(4.6),a _5p ¹⁰ =?1.6(7.3),a _5p ¹² =72.3(2.3),a _6s ¹⁰ =91.7(4.1),b _5p ⁰² =?49.6(1.1) andb _5p ¹¹ =30.4(3.2) (all values in mK). For all calculations in the fs- and hfs-analysis the 5p ²6s ² D _3/2 has to be excluded (see discussion). With the figures given above the quadrupole moment¹²¹ Q(5p ²6s)=?0.44(3) barn was obtained. It is in good agreement with the¹²¹ Q(5p ³). For the core-polarization by the 5p electron in the innerfieldns-shells (n=1, 2, 3, 4, 5) and the unpaired 6s electron a field of +500(300) kG was obtained.     

Sternheimer free determination of the47Ti nuclear quadrupole moment from hyperfine structure measurements

The hyperfine structure (hfs) of 12 metastable states of⁴⁷Ti has been measured by laser induced fluorescence. 11 of these states have been measured additionally very precisely by a laser-rf double resonance method. Taking into account results of earlier hfs measurements, the hfs of altogether 17 fine structure states has been analyzed by the simultaneous parametrization of the one- and two-body interactions in the atomic hfs for the model space (3d+4s) ^N+2 (N=2). This gives 16 parameters for the magnetic dipole interaction and 12 parameters for the electric quadrupole interaction. From the model space parameters, obtained from the hfs fit, the nuclear quadrupole momentQ(⁴⁷Ti)=0.303(24b), has been evaluated at the first time; it is free of Sternheimer corrections up to second order.     

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.     

Knight shift measurements through the NiAsMnP structure change in vanadium monosulfide

Knight-shift data have been obtained for a series of nonstoichiometric VS_x phases with the MnP and NiAs structure types. The data demonstrate that the change in symmetry is accompanied by an abrupt change in the Knight shift indicating that the symmetry change is accompanied by a change in the character of the conduction electrons.     

Isotope shift in hafnium I: Parametric analysis,ab initio calculation,and changes in nuclear charge radii

The isotope shift in the arc spectrum of hafnium was studied in 10 lines for the isotopes¹⁷⁶Hf,¹⁷⁸Hf, and¹⁸⁰Hf by means of a photoelectric recording Fabry-Perot spectrometer with digital data processing. The observed shifts together with results from an earlier study were analyzed by means of the parametric method. The field shift difference between the terms 5d ³(⁴ F) 6s ⁵ F and³ F resulted in 17(2) mK for the isotope pair^178,180Hf. This reflects the influence of a second-order effect which is described by the parameterg ₂=?4.4(6) mK. The parameterz _5d , displaying the magnitude of spin-dependent effects in the isotope shift of 5d ³6s, was found to be 0.8(2) mK for the same isotope pair. The experimental data are compared with results obtained from the non-relativistic Hartree-Fock method. The calculated electron densities describe the experimental field shifts with good accuracy. Hartree-Fock screening ratios for various types of transitions were used to evaluate changes in mean-square nuclear charge radii. The mean value ofλ ^178,180≈δ〈r ²〉^178,180 equals 0.069(10) fm².