135Ba and137Ba Fourier transform NMR and NQR studies

Lutz, O.; Oehler, H.

doi:10.1007/bf01408194

Cited by 37 publications

(3 citation statements)

References 28 publications

(29 reference statements)

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“…We note that a χ 2 minimization of the remaining ratios gives a reduced χ 2 of 1.02 and an estimated ratio of 1.538 425(78) consistent with the reported value of Tables II and III (taken in x axis), x 0 denoting the most accurately reported ratio 1.538 485 in Ref. [32] and δx correspond to errors associated with the respective x values.…”

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confidence: 66%

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Reliability test for the experimental results of electric-quadrupole hyperfine-structure constants and assessment of nuclear quadrupole moments in135Ba and137Ba

2013

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We investigate electric quadrupole hyperfine-structure constant (B) results in 135 Ba + and 137 Ba + and compare their ratios with the reported measurements of the ratio between the nuclear quadrupole moment (Q) values of these isotopes. We carry out confidence tests for the reported experimental B values and calculations of B/Q from the present work. Inconsistencies in the experimental B values are observed in both the isotopes from different experiments performed using the same techniques. The present calculations are carried out using an all order relativistic many-body theory considering only single and double excitations in the coupled-cluster ansatz. After a detailed analysis of the results, the values of Q we obtain for 135 Ba and 137 Ba are 0.153(2)b and 0.236(3)b, respectively, which differ by about 4% from the currently referred precise values.The effective ellipsoidal nuclear charge distribution of an isotope in the nuclear ground state is generally quantified by the nuclear electric-quadrupole moment (Q). The nuclear shell model assumes that the charge distribution is spherically symmetric for a doubly magic closed-shell nucleus, and therefore its quadrupole moment vanishes; otherwise it will have an intrinsic nonzero Q value. Thus, accurate evaluations of Q for different isotopes could probe the shell theory (e.g., see [1]) and therefore the investigation of this quantity has been of considerable interest to nuclear, atomic, and molecular physicists for the last six decades [2][3][4][5][6][7].Although the value of Q for nuclear ground states cannot be measured directly, it is possible to measure their ratios for different isotopes [8][9][10][11]. Also, for an atomic state of a particular isotope, Q can be determined by combining the measured electric-quadrupole hyperfine-structure constant (B) with a calculation of B/Q for that isotope. To obtain an accurate value of Q by this procedure, both the measurement and the calculation have to be performed to high precision. Experimental results are generally considered to be more reliable than the calculated results for many-electron atoms owing to the fact that ab initio evaluation of various physical quantities using many-body methods involve a number of approximations at different stages of the calculations. However, measurements from different experiments are not always in agreement and, in certain cases, large discrepancies between measurements and accurate calculations have been noted [12,13]. It is therefore essential to scrutinize the accuracies of both the experimental B and calculated B/Q results when determining values of Q from them.Studies of hyperfine-structure constants in singly ionized barium (Ba + ) can provide valuable information about the wave functions in the nuclear region and the role of the electron correlation effects whose knowledge are relevant for the proposed parity nonconservation experiments [14]. It is also important for the extraction of higher-order nuclear * bijaya@prl.res.in moments [15]. Furthermore, studies of the hype...

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supporting

confidence: 66%

“…II and III (taken in X-axis), x0 denoting the most accurately reported ratio 1.538485 in Ref. [32] and δx correspond to errors associated with the respective x values.…”

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confidence: 99%

Reliability test for the experimental results of electric-quadrupole hyperfine-structure constants and assessment of nuclear quadrupole moments in135Ba and137Ba

2013

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“…Probably one reason for this situation is the relatively low NMR absolute sensitivity for 137 Ba nuclei (natural abundance of 11.3%) of 7.8×10 −4 compared with that of the protons. For the 135 Ba nuclei the conditions are even worse (6.6% natural abundance, absolute sensitivity of 3.2 × 10 −4 ) as shown in first systematic 135 Ba and 137 Ba Fourier transform NMR and NQR studies on barium salts in aqueous solutions and on polycrystalline solids by Lutz and Oehler [4]. NMR measurements on a polycrystalline material of barium titanate in the cubic phase above the Curie temperature (T C ≈ 408 K, cubic phase with space group P m3m) have been reported by Forbes et al [5].…”

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Barium-137 nuclear magnetic resonance study in the various phases of

Taye

Klotzsche

Michel

et al. 1999

J. Phys.: Condens. Matter

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quadrupole perturbed NMR measurements on a multidomain crystal were performed in order to determine the quadrupole tensors (which are proportional to the electric field gradient (EFG) tensors) in the tetragonal, orthorhombic and rhombohedral phase of . Because of the relatively large quadrupole splitting, only the central transitions were analysed. By means of the well known Volkoff theory the principal values and the directions of the principal axes were evaluated from the angular dependent NMR spectra. Furthermore, the correct determination of the principal values of the quadrupole tensors has been controlled by means of measurements on polycrystalline samples of the same origin. The conclusions from the measurements on the multidomain crystals are in very good agreement with the results of NMR line shape measurements on powdered samples. Moreover, the NMR studies on the crystal sample allow a study of the domain structure in the different ferroelectric phases in complete agreement with the predictions from symmetry considerations.

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