Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

Cho, Herman

doi:10.1016/j.adt.2016.02.003

Cited by 6 publications

(4 citation statements)

References 22 publications

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“…Here, i and j are labels for each of the spin states, i.e., 1 / 2 , 3 / 2 , 5 / 2 , 7 / 2 . More interestingly, numerical solutions (i.e., Δ E ij as well as each E i ) have been tabulated for all η Q values (0 ≤ η Q ≤ 1). − Reciprocally, all the NQR frequencies can be obtained from C Q and η Q . Since antimony possesses two quadrupolar isotopes, a spin- 5 / 2 and a spin- 7 / 2 , five different pure NQR frequencies are available (excluding overtones).…”

Section: Resultsmentioning

confidence: 99%

^121/123Sb Nuclear Quadrupole Resonance Spectroscopy: Characterization of Non-Covalent Pnictogen Bonds and NQR Crystallography

2019

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Pnictogen (or pnicogen) bonding is an attractive interaction between the electrophilic region of group 15 elements (N, P, As, Sb, Bi) and a nucleophile. This interaction for which unique applications in catalysis have recently been uncovered continues to gain popularity. Here, we investigate a series of pnictogen-bonded cocrystals based on SbF3 and SbCl3, prepared via mechanochemical ball milling, with 121/123Sb (I = 5/2 and 7/2, respectively) nuclear quadrupole resonance (NQR) spectroscopy. Observed NQR frequency shifts upon cocrystallization are on the order of 0.1 to 10 MHz and are clearly diagnostic of the formation of pnictogen bonds to antimony. Further evidence for pnictogen bonding is obtained by complementary 13C cross-polarization magic-angle spinning solid-state NMR experiments. DFT calculations of NMR parameters as well as natural localized molecular orbital analyses support the experimental findings and elucidate the electronic origins of the experimental NQR frequency shifts. This work provides insights into the changes in the antimony quadrupolar coupling constant upon pnictogen bonding: strikingly, the decreases noted here parallel those known for hydrogen bonds, but contrast with the increases reported for halogen bonds. The utility of the observed antimony nuclear quadrupolar coupling constants in constraining structural models of cocrystals for which diffraction-based structures are unavailable, i.e., a rudimentary implementation of NQR crystallography, is established. Overall, this work offers a new approach to understand emerging classes of electrophilic interactions and to contextualize them in the broader landscape of established chemical bonding paradigms.

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Section: Resultsmentioning

confidence: 99%

^121/123Sb Nuclear Quadrupole Resonance Spectroscopy: Characterization of Non-Covalent Pnictogen Bonds and NQR Crystallography

2019

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“…The EFG principal component V 33 of a spin- 3 / 2 nuclide can be determined (in SI units) with eq : , where ν is the frequency of the transition at zero field. Assuming that η = 1 based on the 35 Cl and 37 Cl NMR line shapes, the value of V 33 obtained using eq is 0.577 au.…”

Section: Discussionmentioning

confidence: 99%

Equatorial Electronic Structure in the Uranyl Ion: Cs₂UO₂Cl₄ and Cs₂UO₂Br₄

et al. 2021

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Electric field gradient (EFG) tensors in the equatorial plane of the linear UO 2 2+ ion have been measured by nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) experiments and computed by relativistic Kohn−Sham methods with and without environment embedding for Cs 2 UO 2 Cl 4 and Cs 2 UO 2 Br 4 . This approach expands the possibilities for probing the electronic structure in uranyl complexes beyond the strongly covalent U−O bonds. The combined analyses find that one of the two largest principal EFG tensor components at the halogen sites points along the U−X bond (X = Cl, Br), and the second is parallel to the UO 2 2+ ion; in Cs 2 UO 2 Cl 4 , the components are nearly equal in magnitude, whereas in Cs 2 UO 2 Br 4 , due to short-range bromide−cesium interactions, the equatorial component is dominant for one pair of Br sites and the axial component is larger for the second pair. The directions and relative magnitudes of the field gradient principal axes are found to be sensitive to the σ and π electron donation by the ligands and the model of the environment. Chlorine-35 NQR spectra of 235 U-depleted and 235 U-enriched Cs 2 UO 2 Cl 4 exhibited no uranium-isotope-dependent shift, but the resonance of the depleted sample displayed a 58% broader line width.

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“…0 ≤ η ≤ 1 and the larger η becomes, the more mixing there is between sublevels. The Hamiltonian (1) can be diagonalized to find the eigenvalues and eigenvectors, which are shown here for the ground I g = 5/2 and excited (isomer) state I e = 3/2 [45][46][47][48]. Figures 17 and 19 show the energy of the split ground and excited states where C g/e = eQ g/e V zz /(4I g/e (2I g/e −1)).…”

Section: Discussionmentioning

confidence: 99%

Collective effects in Th229 -doped crystals

2018

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Vacuum-ultraviolet-transparent crystals have been proposed as host lattice for the coherent driving of the unusually low-lying isomer excitation in 229 Th for metrology and quantum optics applications. Here the possible collective effects occurring for the coherent pulse propagation in the crystal system are investigated theoretically. We consider the effect of possible doping sites, quantization axis orientation and pulse configurations on the scattered light intensity and signatures of nuclear excitation. Our results show that for narrow-pulse driving, the rather complicated quadrupole splitting of the level scheme is significantly simplified. Furthermore, we investigate complex driving schemes with a combination of pulsed fields and investigate the occurring interference process. Our theoretical results support experimental attempts for first direct driving of the nuclear transition with coherent light.

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Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

Cited by 6 publications

References 22 publications

^121/123Sb Nuclear Quadrupole Resonance Spectroscopy: Characterization of Non-Covalent Pnictogen Bonds and NQR Crystallography

^121/123Sb Nuclear Quadrupole Resonance Spectroscopy: Characterization of Non-Covalent Pnictogen Bonds and NQR Crystallography

Equatorial Electronic Structure in the Uranyl Ion: Cs₂UO₂Cl₄ and Cs₂UO₂Br₄

Collective effects in Th229 -doped crystals

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Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

Cited by 6 publications

References 22 publications

121/123Sb Nuclear Quadrupole Resonance Spectroscopy: Characterization of Non-Covalent Pnictogen Bonds and NQR Crystallography

121/123Sb Nuclear Quadrupole Resonance Spectroscopy: Characterization of Non-Covalent Pnictogen Bonds and NQR Crystallography

Equatorial Electronic Structure in the Uranyl Ion: Cs2UO2Cl4 and Cs2UO2Br4

Collective effects in Th229 -doped crystals

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^121/123Sb Nuclear Quadrupole Resonance Spectroscopy: Characterization of Non-Covalent Pnictogen Bonds and NQR Crystallography

^121/123Sb Nuclear Quadrupole Resonance Spectroscopy: Characterization of Non-Covalent Pnictogen Bonds and NQR Crystallography

Equatorial Electronic Structure in the Uranyl Ion: Cs₂UO₂Cl₄ and Cs₂UO₂Br₄