Hyperfine Structure Parameters Research Articles

The second spectrum of niobium: II. Accurate fine structure study of odd-parity levels

A parametric analysis of the fine structure (FS) and hyperfine structure (HFS) of odd-parity levels of Nb II, involving 11 configurations, has been performed in this work for the first time. The interpretation has been performed based on refined multiconfigurational FS calculations, including the main Rydberg series configurations mutually interacting. The sets of FS parameters, the leading eigenvector percentages of levels, as well as their calculated Landé g-factors, are newly given. The results presented here question the existence of the FS level 4d25s5p 1G4 at an energy of 79 171.731 cm−1 previously reported in the literature. The single-electron HFS parameters are determined in their entirety for the lowest configurations of 93Nb II with a good accuracy and are confirmed by ab initio calculations. For instance, the most influential parameters a5s10 and a4d01 are, respectively, equal to 393.4 (3.2) and 16.06 (0.19) mK for the 4d25s15p1 configuration.

Interaction of Variational Localised Correlation Functions for Atomic Properties of Be I

We present some progress associated to the localised correlation function interaction (LCFI) method. In this report, the LCFI method is tested not only for total energy but also for the specific mass shift operator, the hyperfine structure parameters and the transition probabilities. These properties are computed for the three lowest electronic states of the beryllium atom. These calculations illustrate the importance of the contraction effects.

Energies, Fine Structures, and Hyperfine Structures of the 1s22snp 3P (n=2–4) States for the Beryllium Atom

Energies and wave functions of the 1s22snp 3P (n=2–4) states for the beryllium atom are calculated with the full-core plus correlation wave functions. Fine structures and hyperfine structures are calculated with the first-order perturbation theory. For the 1s22s2p 3P state, the calculated energies, fine structure, and hyperfine structure parameters are in good agreement with the latest theoretical and experimental data in the literature; it is shown that atomic parameters of the low-lying excited states for the beryllium atom can be calculated accurately using this theoretical method. For the 1s22snp 3P (n=3,4) states, the present calculations may provide valuable reference data for future theoretical calculations and experimental measurements.

Analytic Calculation of Isotropic Hyperfine Structure Constants Using the Normalized Elimination of the Small Component Formalism

Based on the normalized elimination of the small component relativistic formalism, a new approach to the calculation of hyperfine structure parameters of paramagnetic molecules is developed and implemented. The new method is tested in the calculation of the isotropic hyperfine structure constant for a series of open-shell molecules containing mercury. The results of calculations carried out in connection with ab initio methods of increasing complexity demonstrate the high accuracy of the formalism developed. In view of its computational simplicity, the new approach provides the basis for an efficient and accurate calculation of the HFS parameters of large molecules.

EPR Studies of Copper-Doped Potassium Dihydrogen Citrate (C6H7KO7) Single Crystal

The magnetic environments of Cu2+-doped potassium hydrogen citrate (C6H7KO7) complex have been identified by electron paramagnetic resonance (EPR) technique. The angular variation of the EPR spectra has shown that three different Cu2+ complexes are located in different chemical environments, and each environment contains one magnetic Cu2+ site occupying substantial positions in the lattice and showing a very high angular dependence. The principal g and the hyperfine structure parameter (A) values of three sets of Cu2+ complex groups are determined. The covalency parameter, mixing coefficients and Fermi-contact term of the complex are obtained, and the ground-state wave function of the Cu2+ ion in the lattice has been constructed.

Theoretical studies of the EPR parameters for Ni2+ and Co+ in MgO

The electron paramagnetic resonance (EPR) parameters (g factors and the hyperfine structure constants) for Ni2+ and Co+ in MgO are theoretically studied from the perturbation formulas of these parameters for a 3d8 ion in octahedral crystal-fields. In the computations, the ligand orbital and spin-orbit coupling contributions are taken into account using the cluster approach. The calculated EPR parameters are in good agreement with the experimental data. The larger g factor and the smaller magnitude of the hyperfine structure constant for Ni2+ as compared with those for Co+ can be attributed to the higher spin-orbit coupling coefficient and the lower dipolar hyperfine structure parameter of the former, respectively.

Ab initio calculations of 14N and 15N hyperfine structures

Hyperfine structure parameters are calculated for the 2p2(3P)3s 4PJ, 2p2(3P)3p 4PoJ and 2p2(3P)3p 4DoJ levels, using the ab initio multiconfiguration Hartree–Fock method. The theoretical hyperfine coupling constants are in complete disagreement with the experimental values of Jennerich et al deduced from the analysis of the near-infrared Doppler-free saturated absorption spectra.

An EPR study of Cu 2+ doped [Na(Hmal)(H 2O) 5] single crystals

The magnetic environments of Cu(2+) doped Na(+) complex have been identified by electron paramagnetic resonance (EPR) technique. The angular variation of the EPR spectra has shown that two different Cu(2+) complexes are located in different chemical environments, and each environment contains one magnetic Cu(2+) site occupying substantial positions in the lattice and showing very high angular dependence. The principal g, and the hyperfine structure parameter (A) values of two sets of Cu(2+) complex groups are determined. The covalency parameter, mixing coefficients and Fermi-contact term of the complex are obtained, and the ground state wave function of the Cu(2+) ion in the lattice has been constructed.

ESR and fluorescence studies of Mn-doped Na 2ZnP 2O 7 single crystal and glasses

X-band electron spin resonance (ESR) spectra and fluorescence measurements were performed on Mn-doped Na2ZnP2O7 (NZPO) single crystal synthesized by the Czochralski pulling method and glasses synthesized by the quenching process. For the single crystal, ESR angular dependences were measured in both the zx and xy plans of the NZPO lattice. The fine and hyperfine structure parameters and g-factor values were determined by modelling the experimental spectra. Using the Newman superposition model, the resonating centres in the single crystal and powder (crushed from crystals) samples are assigned to Mn2+ ions substituting for both zinc and sodium. For the glass sample the analysis of the ESR data shows that Mn2+ ions substitute for the Na+ ions. These interpretations are confirmed by the fluorescence measurements with a unique broad red band for the glassy compound and the presence of two emission bands (green and red) in the case of the crystal sample.

Relativistic calculation of the hyperfine structure parameters for heavy elements and laser detection of the heavy isotopes

The energies and constants of the hyperfine structure for some Li-like multicharged ions, the 133Cs atom and the Cs-like barium ion are calculated within quantum electrodynamics (QED) perturbation theory formalism. The optimal photoionization scheme for detecting the Cs isotopes (nuclei) as products of the 252Cf nuclear spontaneous fission reaction is presented.

Hyperfine-structure studies of the 1s22snp (n=2, 3) 3P states for the beryllium isoelectronic sequence

The hyperfine structure parameters of the 1s22snp (n=2, 3) 3P states for the beryllium isoelectronic sequence from Z= 4 to 10 are calculated with the full-core plus correlation (FCPC) wave functions. For the 1s22s2p 3P state of the beryllium atom, the calculated fine structure parameters are in good agreement with the latest theoretical and experimental data in the literature. It is shown that hyperfine constants of the low-lying excited states for the beryllium atom can be calculated accurately using this theoretical method. For 1s22snp (n=2, 3) 3P states of the beryllium isoelectronic sequence, our predictions may provide valuable reference data for other theoretical calculations and experimental measurements in future.

Wavelengths, energy levels and hyperfine structure constants in Ho ii

We recorded spectra of Ho ii emitted by hollow-cathode lamps, using the ultraviolet Fourier transform spectrometer (FTS) at Lund Observatory and the 2-m FTS at the National Institute of Standards and Technology. The combined wavenumber coverage spans the interval from 8000 to 49 600 cm−1 (12 500 to 2016 Å). We measured 303 lines in these spectra and used them to determine energies and hyperfine structure constants of 100 levels. Of these, 41 energy levels have not been reported previously and hyperfine structure constants have not been reported previously for 83 levels. Comparisons between the hyperfine structure constants and energy levels presented in this article and those previously determined from other studies are included and discrepancies are discussed. A theoretical study of the odd-parity levels leads to hyperfine structure parameters and to predictions for unknown excited levels of the ground-state configuration.

Theoretical investigations of the EPR parameters and local structure for Cu2+ in BeO

The electron paramagnetic resonance (EPR) parameters (the anisotropic g factors, the hyperfine structure parameters and the quadrupole coupling constant Q) and local structure for Cu2+ in BeO are theoretically investigated from the perturbation formulas of these parameters for a 3d9 ion under trigonally distorted tetrahedra. The ligand orbital and spin-orbit coupling contributions are included in the basis of the cluster approach, in view of the strong covalency of the [CuO4]6− cluster. From the calculations, the impurity Cu2+ is suggested not to occupy exactly the ideal Be2+ site but to suffer a slight inward displacement (≈0.024 Å) toward the ligand triangle along the C3 axis. The theoretical EPR parameters show good agreement with the experimental data.

Rotational spectra and hyperfine structure of isotopic species of deuterated cyanoacetylene, DC 3N

Abstract Cyanoacetylene enriched in deuterium was used to record pure rotational transitions of DC 3 N and its rare 13 C and 15 N isotopic species by employing Fourier transform microwave (FTMW) spectroscopy on a supersonic-jet expansion at centimeter wavelengths (8.2–25.4 GHz) and by using long-path absorption spectroscopy at millimeter and submillimeter wavelengths (82–900 GHz). In addition, submillimeter wave measurements (304–897 GHz) have been performed for DC 3 N in its v 7 = 1 lowest excited vibrational state. Hyperfine structure caused by the 14 N and D nuclei has been resolved in the FTMW spectra. Quantum-chemical calculations have been performed on the hyperfine structure parameters at the coupled-cluster level (CCSD(T)) with up to core-polarized quintuple zeta basis-sets and were found to be in excellent agreement with experimental data as far as these were available. Vibrational corrections on the quadrupole coupling parameters have been evaluated at the MP2 level employing a quadruple zeta basis-set. The present and previous data were fit simultaneously to obtain accurate predictions for the identification of these species in space.

SENSING OF NUCLEI AVAILABLE IN LITTLE QUANTITIES BY MEANS OF LASER SPECTROSCOPY OF HYPERFINE STRUCTURE FOR ISOTOPES: NEW THEORETICAL SCHEME (U ,Hg)

It is presented the the effective theoretical scheme with possibility of advancing corresponding nuclear technology for sensing different parameters for nuclei available in the little quantitites. It is based on the experimental receiving the isotope beams on the CERN ISOLDE type apparatus and the precised theoretical and laser spectroscopy empirical estimating the hyperfine structure parameters, magnetic and electric moments of a nuclei of isotopes. As example the nuclei of 235U and 201Hg are considered.

Investigation of the EPR Parameters of a Trigonal Dy3+ Center in La2Mg3(NO3)12 · 24H2O Crystal

The electron paramagnetic resonance parameters g‖ and g⊥ of Dy3+, and the hyperfine structure parameters A‖ and A⊥ of 161Dy3+ and 163Dy3+ in a La2Mg3(NO3)12 · 24H2O crystal are calculated by the perturbation formulas of the EPR parameters for a 4f9 ion in trigonal symmetry. In these formulas, the J-mixing among the 6HJ (J = 15/2, 13/2 and 11/2) states via crystal-field interactions, the mixtures of the states with the same J-value via spin-orbit coupling interaction and the interactions between the lowest Kramers doublet Γγ and the same irreducible representations in the other 20 Kramers doublets ΓX via the crystal-field and orbital angular momentum (or hyperfine structure) are all considered. The crystal-field parameters for the studied Dy3+ center are obtained with the superposition model. The calculated results are in good agreement with the observed values.

Theoretical investigations of EPR parameters for trigonal Sm3+ ion in La2Mg3(NO3)12·24H2O crystal

Abstract The electron paramagnetic resonance parameters g factors g ∥ and g ⊥ of Sm 3+ and hyperfine structure parameters A ∥ and A ⊥ of 147 Sm 3+ and 149 Sm 3+ isotopes in La 2 Mg 3 (NO 3 ) 12 ·24H 2 O crystal are calculated from the perturbation formulas of EPR parameters for 4f 5 ion in trigonal symmetry. In these formulas, the J -mixing among the 6 H J ( J = 5/2, 7/2 and 9/2) states via crystal-field interactions, the mixtures among the states with the same J value via spin–orbit coupling interaction, and the interactions between the lowest Kramers doublet Γγ and the same irreducible representations in the other 11 Kramers doublets Γx via crystal-field and orbital angular momentum (or hyperfine structure) interactions are considered. The crystal-field parameters for the studied Sm 3+ centre are obtained from the superposition model. The theoretical calculated results are in reasonable agreement with the experimental values.

Manganese Abundances in Cluster and Field Stars

We have derived Mn abundances for more than 200 stars in 19 globular clusters. In addition, Mn abundance determinations have been made for a comparable number of halo field and disk stars possessing an overlapping range of metallicities and stellar parameters. Our primary data set was comprised of high-resolution spectra previously acquired at the McDonald, Lick, and Keck Observatories. To enlarge our data pool, we acquired globular and open cluster spectra from several other investigators. Data were analyzed using synthetic spectra of the 6000 Å Mn I triplet. Hyperfine structure parameters were included in the synthetic spectra computations. Our analysis shows that for the metallicity range -0.7 > [Fe/H] > -2.7, stars of 19 globular clusters have a mean relative abundance of = -0.37 ± 0.01 (σ = 0.10), a value in agreement with that of the field stars, = -0.36 ± 0.01 (σ = 0.08). Despite the 2 orders of magnitude span in metallicity, the ⟨[Mn/Fe]⟩ ratio remains constant in both stellar populations. Our Mn abundance data indicate that there is no appreciable variation in the relative nucleosynthetic contribution from massive stars that undergo core-collapse supernovae and thus no significant change of the associated initial mass function in the specified metallicity range.

Theoretical Studies on Dications and Trications of FH, ClH, and BrH. Properties of the Bound 15Σ- States. Electron-Spin g-Factors and Fine/Hyperfine Constants of the Metastable X3Σ- States of ClH2+ and BrH2+

This theoretical study reports calculations on the fine and hyperfine structure parameters of the metastable X(3)Sigma(-)(sigma(2)pi(2)) state of ClH(2+) and BrH(2+). Data on the repulsive FH(2+) system are also included for comparison purposes. The hyperfine structure (hfs) coupling constants for magnetic (A(iso), A(dip)) and quadrupole (eQq) interactions are evaluated using B3LYP, MP4SDQ, CCSD, and QCISD methods and several basis sets. The fine structure (fs) constants (zero-field splitting lambda and spin-rotation coupling gamma) and electron-spin magnetic moments (g-factor) are evaluated in 2nd-order perturbation theory using multireference CI (MRCI) wave functions. Our calculations find for (35)Cl of ClH(2+) A(iso)/A(dip) = 110/-86 MHz; eQq(0) = -59 MHz; 2lambda = 20.4 cm(-1); g( perpendicular)(v = 0) = 2.02217; and gamma = -0.31 cm(-1) (to be compared with the available experimental A(iso)/A(dip)= 162/-30 MHz). For (79)BrH(2+), the corresponding values are 300/-400 MHz; 368 MHz; 362.6 cm(-1); 2.07302; and -0.98 cm(-1) (experimental 2lambda = 445(+/-80) cm(-1)). We find g( perpendicular)(ClH(2+)) to increase by about 0.0054 between v = 0 and 2, whereas the experimental effective g( perpendicular) changes drastically with vibrational excitation. Nuclear quadrupole coupling constants for halogen atoms X are found to be as large as corresponding A(dip)(X)'s, indicating that both terms may have to be included in the Hamiltonian used to interpret XH(2+) hyperfine spectra. A novel finding relates to the bound character of the 1(5)Sigma(-)(sigmapi(2)sigma) state in FH(2+), as already known for ClH(2+) and BrH(2+), but having a deeper potential well D(e) approximately 4,000 cm(-1) (versus 1,000 cm(-1) in the heavier radicals). Vertical ionization potentials for formation of XH(3+) trications are also discussed.

Investigations of the spin-Hamiltonian parameters for Er 3+ at the Th 4+ site in ThGeO 4

The spin-Hamiltonian (SH) parameters g factors g(parallel), g(perpendicular) and the hyperfine structure parameters A(parallel) and A(perpendicular) for Er3+ at the tetragonally distorted dodecahedral Th4+ site in ThGeO4 are theoretically investigated by using the perturbation formulas of the SH parameters for a 4f11 ion in tetragonal symmetry. In these formulas, the contributions to the SH parameters from the second-order perturbation terms and the admixture of various energy levels are taken into account. The related crystal-field parameters are calculated from the geometrical relationship of the impurity center and the superposition model. Based on the studies, the lowest Kramers doublet is found to be Gamma7, rather than Gamma6 suggested in the previous work. The calculated SH parameters for Gamma7 doublet in this work are smaller than those obtained for Gamma6 doublet in the previous work and in good agreement with the observed values. The various contributions to the SH parameters are discussed.