Hyperfine spectrum of NaF

The molecular beam electric resonance technique has been used to conduct a high precision examination of the hyperfine spectrum of ²³Na¹⁹F. Coupling constants for the nuclear electric quadrupole interactions, the spin-rotation interactions, the tensor and scalar spin-spin interactions, and their dependence on vibrational and rotational state have been determined.     

Analysis of the nuclear quadrupole interaction of Disulfur Dichloride, S2Cl2

Pure rotational spectra of S₂³⁵Cl₂ and S₂³⁵Cl³⁷Cl have been observed using a Fourier-transform microwave spectrometer. An analysis of the hyperfine structure made by considering the nuclear spin statistics showed that S₂Cl₂ has C₂symmetry, where the hyperfine splittings due to the two Cl nuclei were analyzed precisely. The nuclear quadrupole coupling constants including the off-diagonal (χ_ab, χ_ac, χ_bc) components and the nuclear spin–rotation interaction constants associated with the two Cl nuclei have been determined for the first time. We have shown that the nuclear quadrupole interaction plays an important role in the ortho–para mixing.     

Molecular relativistic electric field gradient calculations suggest revision of the value of the nuclear electric quadrupole moment of 127I

Relativistic ab initio methods are used to compute the electric field gradient at the iodine nucleus in nine different closed-shell diatomic molecules. Combining these theoretical electric field gradients with experimental nuclear quadrupole coupling constants gives a consistent value of the nuclear quadrupole moment of ¹²⁷I of—696(12)millibarn. We argue that this value is more precise than the current standard value of the nuclear quadrupole moment of ¹²⁷I and recommend adjusting the reference value accordingly. The precision of this determination is still determined by technical limitations in the theoretical work, in particular the neglect of the two-electron Gaunt interaction in the Hamiltonian and correlation contributions beyond those described at the CCSD(T) level of theory, but the errors are reduced relative to the theoretical work that underlies the current standard value of this nuclear quadrupole moment. As a secondary study we also considered the calculation of the small electric field gradient at the gold nucleus in the AuI molecule and conclude that this computation remains a challenge for theoreticians.     

Attenuation of Nuclear Orientation of 127In in Gd and the InGd Korringa Spin–Lattice Relaxation Time Constant

The nuclear spin–lattice relaxation of ¹²⁷In implanted into pure gadolinium metal has been measured using the method of integral attenuation of on-line nuclear orientation. The Korringa constant is determined to be C_K (¹²⁷InGd, B_pol = 0.5 T) = 0.133(18) sK. The result is compared with relaxation of In nuclei inFe.     

Λ spin–orbit splitting in heavy hypernuclei as deduced from DWIA analyses of the reaction

By taking nuclear core excitations into account, detailed structure calculations of ⁸⁹ _ΛY have been performed as a function of the Λ spin–orbit splitting. The obtained wave functions have been used to estimate the (π⁺,K⁺) reaction cross sections within the distorted-wave impulse approximation (DWIA). A theoretical explanation is given quantitatively for the first time of how to understand the doublet substructure of each major peak observed in medium-heavy hypernuclear production. A small Λ spin–orbit splitting of around δ(0f^Λ)=0.2 MeV is deduced, a value consistent with the small ΛN two-body spin–orbit interactions deduced from γ-ray measurements in three light hypernuclei.     

Microwave observation of 41K79Br and 41K81Br from laser-ablated potassium bromide

The J = 2 ← 1 transitions of the previously unobserved isotopologues ⁴¹K⁷⁹Br and ⁴¹K⁸¹Br have been recorded with a pulsed-nozzle Fourier transform microwave spectrometer, newly combined with a 532 nm laser ablation source. Aspects of the experimental design are described. Rotational and nuclear quadrupole coupling constants are obtained and combined with published results for ³⁹K⁷⁹Br and ³⁹K⁸¹Br to produce a set of isotopically invariant parameters. New rotational transitions of ²³Na^35,37Cl, ³⁹K⁷⁹Br, and ³⁹K¹²⁷I have also been recorded. Excited vibrational states are not observed, indicating efficient cooling of the metal halides following the initial ablation event.     

Investigation of the system TeSn by the combined hyperfine interaction method

Perturbed angular distribution measurements in a tin target have been performed for the^{121, 123} Te (7/2⁺) and¹¹⁵Te (11/2^–) isomeric levels subject to a combined magnetic and electric quadrupole interaction. Strong quadrupole interactions attributed to nearby defects, as well as weak interactions due to further located defects, were observed. The ratio of the electric quadrupole moments |Q|(7/2⁺,¹²¹Te)/ |Q|(11/2^–,¹¹⁵Te)=1.1(2) was also obtained.     

Hyperfine spectrum of RbI

The molecular beam electric resonance technique has been used to conduct a high precision examination of the hyperfine spectrum of RbI. Coupling constants for the nuclear electric quadrupole interactions, the spin-rotation interactions, the tensor and scalar spin-spin interactions, and their dependence on vibrational and rotational state have been determined.     

Phase transitions and127I,133Cs quadrupole couplings in polycrystalline Cesium metaperiodate

The¹²⁷I and¹³³Cs NMR spectra of polycrystalline CsIO₄, a material of potential interest for transformation of laser irradiation, have been measured in the temperature range 170–440 K and the line shape has been analyzed taking into account first and second order quadrupole interactions and chemical shift anisotropy. Quadrupole coupling constants and asymmetry parameters have been determined as a function of temperature.¹²⁷I and¹³³Cs data consistently show two phase transitions in the ranges 243–300 K and 420–440 K with a temperature hysteresis for the first transition and a range for coexistence of two phases. The time evolution of the NMR signal suggests the existence of piezomagnetism, which was believed to exist only in crystals with a magnetic structure.     

Nuclear quadrupole interaction of119mHg in mercury(I) and mercury(II) halides

The nuclear quadrupole interactions of^199mHg in the mercury(I) and mercury(II) halides with Cl, Br, I were determined by time differential perturbed angular correlation. The quadrupole moment of theI=5/2 state in¹⁹⁹Hg was redetermined to beQ _5/2=0.674(77) b. The nuclear quadrupole interaction in both mercurous and mercuric halides scales with the electronegativity. Electric field gradients at mercury and halogen sites were calculated by a full-potential linearized augmented plane wave method (WIEN code) and were found in good agreement with experiment. In some cases a total energy minimization for internal parameters was carried out and found to be essential.     

Microwave spectra of eight isotopic modifications of 1-chloro-1-fluoroethylene

The rotational spectra of eight isotopomers of 1-chloro-1-fluoroethylene in the 6-22 GHz region have been collected and analyzed. Each rotational transition is split into hyperfine components by the chlorine (either ³⁵Cl or ³⁷Cl) nuclear quadrupole coupling interaction and additionally, one or more smaller interactions such as the spin-rotation interaction due to the fluorine atom, hydrogen-hydrogen spin-spin coupling interactions, and in appropriately substituted species, the deuterium nuclear quadrupole hyperfine interaction. The rotational constants derived from these isotopomers allow the determination of average and Kraitchman substitution structures for 1-chloro-1-fluoroethylene, whereas the availability of the diagonal chlorine nuclear quadrupole coupling constants for all the isotopomers provides complete quadrupole coupling tensors for both ³⁵Cl and ³⁷Cl. In the course of this work, the rotational spectrum of an excited vibrational state of the normal isotopomer was observed, which ab initio calculations suggest should be assigned to ν₉=1, an in-plane bending motion at the CFCl end of the molecule.     

127I Mössbauer study of some oxygen bonded iodine(I) and iodine(III) complexes

¹²⁷I Moessbauer spectra have been recorded at 4.2°K for a series of oxygen bonded iodine(I) and iodine(III) complexes. The sign of the quadrupole coupling constant is dependant only on the primary arrangement of ligands about the central iodine nucleus whereas the magnitude and the asymmetry parameter are more sensitive to ligand electronegativity and type.     

Study of nuclear quadrupole interactions and quadrupole Raman processes of Ga and Ga in a β-Ga2O3:Cr single crystal

Nuclear magnetic resonance (NMR) data and the spin–lattice relaxation times, T₁, of ⁶⁹Ga and ⁷¹Ga nuclei in a β-Ga₂O₃:Cr³⁺ single crystal were obtained using FT NMR spectrometry. Four sets of NMR spectra for ⁶⁹Ga (I = 3/2) and ⁷¹Ga (I = 3/2) were obtained in the crystallographic planes. The ⁶⁹Ga and ⁷¹Ga nuclei each had two chemically inequivalent Ga_I and Ga_II centers. Each of the ⁶⁹Ga and ⁷¹Ga isotopes yielded two different central NMR resonance lines originating from Ga_I and Ga_II sites. The nuclear quadrupole coupling constants and asymmetry parameters of ⁶⁹Ga_I, ⁶⁹Ga_II, ⁷¹Ga_I, and ⁷¹Ga_II centers in a β-Ga₂O₃:Cr³⁺ crystal were obtained. Analysis of the EFG tensor principal axes (PAs) for Ga nuclei and the ZFS tensor PAs for the Cr³⁺ ion confirmed that the Cr³⁺ paramagnetic impurity ion substitutes for the Ga³⁺ ion in the oxygen octahedron. In addition, the temperature dependencies of the ⁶⁹Ga and ⁷¹Ga relaxation rates were consistent with Raman processes, as T₁⁻¹ ∝ T². Even though the Cr³⁺ impurities are paramagnetic, the relaxations were dominated by electric quadrupole interactions of the nuclear spins in the temperature range investigated.     

Directional behavior of nuclear quadrupole resonance in YBa2Cu3O6

Powder samples of YBa₂Cu₃O₆ were magnetically aligned and the anisotropies in the systems were studied by means of Cu(1) nuclear quadrupole resonance (NQR) in the absence of external magnetic fields. Our room temperature measurements of the NQR lineshapes and the spin–lattice and spin–spin relaxation times as a function of the aligning magnetic field indicate that full microscopic alignment can be achieved by using a magnetic field of about 4.7 T, for which doublet line patterns arising from a hyperfine splitting were observed.     

Sensitivity of nuclear-quadrupole double-resonance detection of half-integer spin nuclei

The sensitivity of the Slusher and Hahn’s nuclear quadrupole double resonance technique is calculated in general for an arbitrary nuclear spin S of the quadrupole nuclei and for an arbitrary asymmetry parameter η of the electric field gradient tensor. The nuclear spin S = 5/2 (¹⁷O, ²⁵Mg, …) is treated in details. The influence of the cross-relaxation rate between the quadrupole nuclei and the abundant spin system on the sensitivity of double resonance is discussed. The results of the theoretical analysis are applied in the analysis of the ¹H–¹⁷O nuclear quadrupole double resonance spectra in p-toluenesulfonamide and 2-nitrobenzoic acid. The 17O nuclear quadrupole resonance frequencies from a sulfonamide group are determined for the first time. The proton–oxygen cross-relaxation rates and the proton local frequency in zero external magnetic field are experimentally determined from the nuclear quadrupole double resonance spectra.     

Year-2017 nuclear quadrupole moments

A ‘year-2017’ set of nuclear quadrupole moments, Q, is presented. Compared to the previous, ‘year-2008’ set, a major revision of the value, or an improvement of the accuracy is reported for ²₁H, ^{37, 39}₁₈Ar, ^{39, 40, 41}₁₉K, ⁶⁷₃₀Zn, ₄₈Cd, ₄₉In, ₅₀Sn (Mössbauer state), ₅₁Sb, ₈₇Fr and ₉₀Th. Slight improvements or valuable reconfirmations exist for ₄Be, ₆C, ₁₆S, ₁₇Cl, ₃₃As, ₃₅Br, ₅₃I, ₅₄Xe, ₅₆Ba, ₅₇La and ₇₂Hf.     

Theory of electronic light scattering in lateral superlattices with Rashba spin–orbit coupling under quantizing electric and magnetic fields

The influence of an in-plane electric and out-of-plane magnetic field on the electronic light scattering is calculated for a lateral semiconductor superlattice within Rashba spin–orbit interaction. Sharp resonances are predicted to appear when the Raman shift matches one frequency of the Wannier–Stark ladder. The spin–orbit interaction gives rise to a dispersion of the exact one-particle eigenstates and an associated finite width of the Raman line, which can be tuned by the electric and magnetic field. When the Bloch frequency is located in this Raman line, a Fano resonance is observed.     

Production of Nuclear Polarization of Na Isotopes at ISAC/TRIUMF and its Hyperfine Interaction

Hyperfine interactions of Na isotopes in single crystals have been studied using highly nuclear polarized ^{20,21,26,27,28}Na beams provided by ISAC/TRIUMF. The degree of polarization kept in the crystals, the spin-lattice relaxation times, the electric quadrupole coupling constants and the initial distribution of the populations were measured. Such knowledge is indispensable for the application of the hyperfine interactions in the study of precision measurements such as the nuclear structure through nuclear moments and the fundamental symmetries.     

A study of deuteron quadrupole moment effects in sub-coulomb scattering of tensor polarized deuterons

Measurements of the tensor analyzing power T₂₀ are presented for deuteron elastic scattering from ²⁰⁸Pb at energies below the Coulomb barrier. It is found that, for energies below about 7 MeV, T₂₀ arises primarily from the interaction of the deuteron quadrupole moment with the nuclear electric field gradient. Contributions to T₂₀ from nuclear interactions with the target are shown to be very small for E_d ? 5 MeV. Measurements of T₂₀ at E_d = 4 MeV, accurate to ± 8 × 10^?5, are presented. After correcting for deuteron stretching and a number of additional small effects, the data are used to make a new determination of the quadrupole moment. The result, Q = 0.282 ± 0.019 fm², is in good agreement with the conventional value deduced from molecular hyperfine structure data.     

Methyl and t-butyl reorientation in an organic molecular solid

We have determined the molecular and crystal structure of 4,5-dibromo-2,7-di-t-butyl-9,9-dimethylxanthene and measured the ¹H spin–lattice relaxation rate from 87 to 270 K at NMR frequencies of ω/2π=8.50, 22.5, and 53.0 MHz. All molecules in the crystal see the same intra and intermolecular environment and the repeating unit is half a molecule. We have extended models developed for ¹H spin–lattice relaxation resulting from the reorientation of a t-butyl group and its constituent methyl groups to include these rotors and the 9-methyl groups. The relaxation rate data is well-fitted assuming that the t-butyl groups and all three of their constituent methyl groups, as well as the 9-methyl groups all reorient with an NMR activation energy of 15.8±1.6 kJ mol⁻¹ corresponding to a barrier of 17.4±3.2 kJ mol⁻¹. Only intramethyl and intra-t-butyl intermethyl spin–spin interactions need be considered. A unique random-motion Debye (or BPP) spectral density will not fit the data for any reasonable choice of parameters. A distribution of activation energies is required.