Nuclear Magnetic Quadrupole Research Articles

Solid‐state nuclear magnetic resonance and nuclear quadrupole resonance as complementary tools to study quadrupolar nuclei in solids

AbstractSolid‐state nuclear magnetic resonance (SSNMR) spectroscopy has largely overtaken nuclear quadrupole resonance (NQR) spectroscopy for the study of quadrupolar nuclei. In addition to information on the electric field gradient, SSNMR spectra may offer additional information concerning other NMR interactions such as magnetic shielding. With continued technological advances contributing to developments such as higher magnetic fields, SSNMR boasts several practical advantages over NQR. However, NQR is still a relevant technique, as it may often be the most practical approach in cases of extremely large quadrupolar coupling constants. Here, we discuss the advantages and disadvantages of SSNMR and NQR spectroscopies, with the quadrupolar halogens serving as examples. The purpose of this article is to serve as a guide on using SSNMR and NQR as complementary tools, covering some of their practicalities, limitations, and experimental challenges.

CO2 adsorption on the surface and open ended of Single wall carbon nanotubes (SWCNTs): A Comparative study

Adsorption of CO2 on the surface of Single-wall zigzag (5,0) and armchair (4,4) carbon nanotubes (SWCNTs) were studied through using density functional theory (DFT) calculations. Optimizations of geometric were performed at the B3PW91 level of 6-311++G** method standard basis set using GAUSSIAN 03 package of program [1]. Structural models were optimized and adsorption energies, band gap, charge transfer and dipole momentum were obtained to investigate the nuclear magnetic resonance (NMR) and Nuclear Quadrupole Resonance (NQR) spectroscopy parameters for (CO2-CNTs) model of zigzag (5,0) and armchair (4,4) SWCNTs. Comparison of the results of the zigzag and armchair models with calculated chemical shielding, electric filed gradient tensors at the sites of carbon on the Surface and open ended revealed that CO2 adsorption has a dramatic effect on the electronic structure of SWCNTs and the more adsorption on the surface is about -1.5747eV SWCNT-S (5, 0) nanotube.

DFT Studies of NH-Cl Hydrogen Bond of Amino Acid Hydrochloride Salts in Ion Channels.

Quantum chemical calculations were made, to study NH-Cl hydrogen bonds of two amino acid hydrochloride salts called alanine and threonine. The Nuclear Magnetic Resonance and Nuclear Quadrupole Resonance parameters for nitrogen and chlorine were calculated via four functionals such as, B3LYP, M062X, M06L, and CAM-B3LYP and by applying the 6-311++G(d,p) basis set. One of the functionals produced more accurate results. Geometry optimization was performed using the M062X/6-31++G(d,p) method, and Natural Bond Orbitals analysis was performed by applying the M062X/6-311++G(d,p) level. This study examined Nuclear Magnetic Resonance and Nuclear Quadrupole Resonance parameters with changes in structure from monomer to pentamer and investigated correlations between Natural Bond Orbitals parameters and Nuclear Magnetic Resonance or Nuclear Quadrupole Resonance parameters. The Natural Bond Orbitals parameters were used to investigate changes in structural parameters along with crystal development.

Volovik effect and Fermi-liquid behavior in thes-wave superconductorCaPd2As2: As75NMR-NQR measurements

The electronic and magnetic properties of the collapsed-tetragonal CaPd$_2$As$_2$ superconductor (SC) with a transition temperature of 1.27 K have been investigated by $^{75}$As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. The temperature ($T$) dependence of the nuclear spin lattice relaxation rates (1/$T_1$) and the Knight shifts indicate the absence of magnetic correlations in the normal state. In the SC state, 1/$T_1$ measured by $^{75}$As NQR shows a clear Hebel-Slichter (HS) peak just below $T_{\rm c}$ and decreases exponentially at lower $T$, confirming a conventional $s$-wave SC. In addition, the Volovik effect, also known as Doppler shift effect, has been clearly evidenced by the observation of the suppression of the HS peak with applied magnetic field.

Analysis of 27Al- and 93Nb-NMR spectra of PrNb2Al20 single crystal

We report the results of 27Al- and 93Nb- nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements in PrNb2Al20 single crystals. The field angle dependence of the observed 93Nb-NMR lines for the single crystal at around 5 T and at 50 K is reproduced by a simulation using previously reported NQR parameters νQ,Nb ≈ 1.82 MHz and ηNb ≈ 0, while 27Al-NMR lines were not reproduce by the previously reported NQR parameters νQ,Al(3) ≈ 1.53 MHz and ηAl(3) ≈ 0.17. By reexamining and reconsidering the NMR and NQR lines for powder samples, we obtained a correct NQR parameters for Al(3) site to be νQ,Al(3),new ≈ 1 MHz and ηAl(3),new ≈ 0.4.

Erratum: TaN molecule as a candidate for the search for aT, P-violating nuclear magnetic quadrupole moment [Phys. Rev. A92, 012521 (2015)

Received 18 November 2015DOI:https://doi.org/10.1103/PhysRevA.92.069901©2015 American Physical Society

Ferromagnetic Spin Fluctuation and Unconventional Superconductivity in Rb2Cr3As3 Revealed by 75As NMR and NQR.

We report (75)As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) studies on the superconductor Rb(2)Cr(3)As(3) with a quasi-one-dimensional crystal structure. Below T∼100 K, the spin-lattice relaxation rate (1/T(1)) divided by temperature, 1/T(1)T, increases upon cooling down to T(c)=4.8 K, showing a Curie-Weiss-like temperature dependence. The Knight shift also increases with decreasing temperature. These results suggest ferromagnetic spin fluctuation. In the superconducting state, 1/T(1) decreases rapidly below T(c) without a Hebel-Slichter peak, and follows a T(5) variation below T∼3 K, which points to unconventional superconductivity with point nodes in the gap function.

16pDC-2 Sr_2RuO_4の核磁気共鳴・核四重極共鳴による超伝導状態の研究

16pDC-2 Sr_2RuO_4の核磁気共鳴・核四重極共鳴による超伝導状態の研究

TaN molecule as a candidate for the search for aT,P-violating nuclear magnetic quadrupole moment

It is demonstrated that the TaN molecule is the best candidate to search for T,P-violating nuclear magnetic quadrupole moment (MQM), it also looks promising to search for other T,P-odd effects. We report results of coupled-cluster calculations of T,P-odd effects in TaN produced by the Ta nucleus MQM, electron electric dipole moment (EDM), scalar$-$pseudoscalar nucleus$-$electron interactions, also of the molecule-axis hyperfine structure constant and dipole moment. Nuclear calculations of $^{181}$Ta MQM are performed to express the T,P-odd effect in terms of the strength constants of T,P-odd nuclear forces, proton and neutron EDM, QCD parameter $\theta$ and quark chromo-EDM.

Magnetic and Electronic Properties of URu2Si2 Revealed by Comparison with Nonmagnetic References ThRu2Si2 and LaRu2Si2

We have carried out nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements on ThRu2Si2 and LaRu2Si2, which are the nonmagnetic references of the intriguing heavy fermion URu2Si2. The comparisons of URu2Si2 with the reference materials allow us to analyze the already known NMR and NQR data on URu2Si2 phenomenologically and semiquantitatively. The study of 101Ru-NQR frequency suggests the relatively close electronic configuration of URu2Si2, including the valence of the actinide ion, to that of the tetravalent ThRu2Si2 at high temperatures, as well as the delocalization of 5f electrons at low temperatures. Ising-like spin fluctuations along the c-axis were brought to light by 29Si-NMR data in the so-called hidden order phase of URu2Si2. The unique magnetic property is plausibly associated with the mechanism of the unconventional superconductivity.

Isolation and identification of chemical constituents from Origanum majorana and investigation of antiproliferative and antioxidant activities.

Origanum majorana L., belonging to the Lamiaceae family, has great potential and has been used as a folk medicine against asthma, indigestion, headache and rheumatism; in addition, the essential oils of this plant have been used widely in the food industry. Plant materials have been harvested from the Medicinal and Aromatic Plant Field of Gaziosmanpasa University. Air-dried plant materials were boiled in water, filtered, and the solvent part subsequently extracted with hexane and ethyl acetate. The chromatographic method was applied to the ethyl acetate extract to isolate bioactive secondary metabolites, the structures of which were elucidated by spectroscopic techniques: basically one-dimensional and two-dimensional nuclear magnetic resonance and quadrupole time-of-flight liquid chromatography. Antiproliferative and antioxidant activities of isolated secondary metabolites were determined. 5,6,3'-Trihydroxy-7,8,4'-trimethoxyflavone, hesperetin, hydroquinone, arbutin and rosmarinic acid were isolated from the water-soluble ethyl acetate extract of aerial parts of O. majorana. Antioxidant activities of isolated compounds and water-soluble ethyl acetate extract were investigated using assays of DPPH(•), ABTS(•+), reducing power and total phenolic content. Antiproliferative activities of the isolated compounds and plant extracts were investigated against C6 and HeLa cell lines using BrdU cell proliferation enzyme-linked immunosorbent assay and xCELLigence assay, respectively. Both hesperetin and hydroquinone were determined to have stronger antiproliferative activities against C6 and HeLa cells than the other isolated compounds and 5-fluorouracil. The results showed that the extract and isolated compounds exhibited significant antioxidant activities. Hence this plant has the potential to be a natural antioxidant in the food industry and an anticancer drug.

Characterization of Hydrogen Bonds in the End-Functionalized Single-Wall Carbon Nanotubes: A DFT Study

A systematic computational study is carried out to shed some light on the structure of semiconducting armchair single-wall carbon nanotubes (n, n) SWCNTs, n = 4, 5 and 6, functionalized at the end with carboxyl (– COOH ) and amide (– CONH 2) from the viewpoint of characterizing the intramolecular hydrogen bondings at the B3LYP/6-31++G(d, p) level. Geometry parameters display different types of intramolecular hydrogen bonding possibilities in the considered functionalized SWCNTs. All of the hydrogen bondings are confirmed by natural bonding orbitals (NBO) analysis as well as nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) parameters. Based on NBO analysis, the calculated [Formula: see text] delocalization energies E(2), 1.15 kcal/mol to 7.04 kcal/mol, are in direct relation with the hydrogen bonding strengths. Differences in the chemical shielding principal components of 13 C and 17 O nuclei correlate well with the strengths of the hydrogen bondings. Participating in stronger hydrogen bondings, a larger SWCNT has a decreasing effect on 13 C (= O ) and 17 O isotropic chemical shieldings, σiso, consistent with the NBO analysis. The considerable changes of 13 C /17 O σiso can be interpreted as a result of shielding tensor component orientation. The 13 C (= O ) and 17 O quadrupole coupling constants C Q decrease under the effect of hydrogen bonding while asymmetry parameters ηQ significantly increase, indicating that 17 O ηQ is more sensitive to hydrogen bondings.

Zero-field NMR and NQR studies of magnetically ordered state in charge-ordered EuPtP

EuPtP undergoes two valence transitions and has two kinds of valence states of Eu ions at low temperatures. In the charge-ordered state, this compound shows an antiferromagnetic order ascribed to magnetic divalent Eu ions. We investigated the antiferromagnetically ordered state of EuPtP by nuclear magnetic resonance (NMR) measurement and nuclear quadrupole resonance (NQR) measurement in a zero external magnetic field. The observed $^{153}\mathrm{Eu}$ NMR signals of a magnetic divalent state and $^{151,153}\mathrm{Eu}$ NQR signals of a nonmagnetic trivalent state clearly demonstrate that the spins order in the hexagonal basal plane and the internal magnetic field is not canceled out, even at the ${\mathrm{Eu}}^{3+}$ layers which are in the middle of magnetic ${\mathrm{Eu}}^{2+}$ layers. In addition, the observation of ${}^{31}\mathrm{P}$ and $^{195}\mathrm{Pt}$ NMR spectra allowed us to discuss a possible magnetic structure. We also evaluated the nuclear quadrupole frequencies for both ${\mathrm{Eu}}^{2+}$ and ${\mathrm{Eu}}^{3+}$ ion states.

CP-violating effect of the Th nuclear magnetic quadrupole moment: accurate many-body study of ThO.

Investigations of CP violation in the hadron sector may be done using measurements in the ThO molecule. Recent measurements in this molecule improved the limit on the electron electric dipole moment (EDM) by an order of magnitude. Another time-reversal (T) and parity (P)-violating effect in 229ThO is induced by the nuclear magnetic quadrupole moment. We perform nuclear and molecular calculations to express this effect in terms of the strength constants of T, P-odd nuclear forces, neutron EDM, QCD vacuum angle θ, quark EDM, and chromo-EDM.

Parity-violating interactions of cosmic fields with atoms, molecules, and nuclei: Concepts and calculations for laboratory searches and extracting limits

We propose methods and present calculations that can be used to search for evidence of cosmic fields by investigating the parity-violating effects, including parity nonconservation amplitudes and electric dipole moments, that they induce in atoms. The results are used to constrain important fundamental parameters describing the strength of the interaction of various cosmic fields with electrons, protons, and neutrons. Candidates for such fields are dark matter (including axions) and dark energy, as well as several more exotic sources described by standard-model extensions. Existing parity nonconservation experiments in Cs, Dy, Yb, and Tl are combined with our calculations to directly place limits on the interaction strength between the temporal component, b_0, of a static pseudovector cosmic field and the atomic electrons, with the most stringent limit of |b_0^e| < 7*10^(-15) GeV, in the laboratory frame of reference, coming from Dy. From a measurement of the nuclear anapole moment of Cs, and a limit on its value for Tl, we also extract limits on the interaction strength between the temporal component of this cosmic field, as well as a related tensor cosmic-field component d_00, with protons and neutrons. The most stringent limits of |b_0^p| < 4*10^(-8) GeV and |d_00^p| < 5*10^(-8) for protons, and |b_0^n| < 2*10^(-7) GeV and |d_00^n| < 2*10^(-7) for neutrons (in the laboratory frame) come from the results using Cs. Axions may induce oscillating P- and T-violating effects in atoms and molecules through the generation of oscillating nuclear magnetic quadrupole and Schiff moments, which arise from P- and T-odd intranuclear forces and from the electric dipole moments of constituent nucleons. Nuclear-spin-independent parity nonconservation effects may be enhanced in diatomic molecules possessing close pairs of opposite-parity levels in the presence of time-dependent interactions.

Presentation Quantum Computation Based on Many Level Quantum System and SU(n) Cohered States and Qubit, Qutrit and Qubit Using Nuclear Magnetic Resonance Technique and Nuclear Quadrupole Resonance

In this article we have considered the effect of a magnetic field, the Zeeman effect, nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) on nuclei with spin S  ½ looked. Then energy levels, transition frequencies and the energy spectra for the nuclear spins have specified. After using the group definition SU(2), SU(3), SU(4), SU(N) OR SU(2S+1), In quantum mechanics and quantum computation the range nuclear energy levels sin to one qubit, qutrit and qudit assign. We have defined the quantum states.

A new liquid chromatography–fluorescence method for determination of perfluorooctanesulphonyl fluoride upon derivatisation with 1-naphthol

Perfluorooctanesulphonyl fluoride (PFOSF), as a main precursor of perfluorooctanesulphonate (PFOS) that is ubiquitous in the environment, has been released to the environment with substantial quantity. Determination of PFOSF presents significant analytical challenges for using liquid chromatography with UV (LC–UV) and fluorescence detection (LC–FLD) due to the lack of chromophore in the molecular structure. In this study, a new method was developed by derivatising PFOSF with 1-naphthol to form 1-naphthylperfluorooctanesulphonate (NPFOS), which allowed rapid qualitative and quantitative analysis using LC–UV and LC–FLD. The derivatising product was confirmed from the analyses by proton nuclear magnetic resonance and quadrupole–time of flight mass spectrometry. The LC–FLD method demonstrated good linearity in the NPFOS concentration range from 20 pg µL−1 to 20 ng µL−1 with a correlation coefficient better than 0.999, with the instrument detection limit of 1.5 pg µL−1.

Time-reversal symmetry violation in molecules induced by nuclear magnetic quadrupole moments.

Recent measurements in paramagnetic molecules improved the limit on the electron electric dipole moment (EDM) by an order of magnitude. Time-reversal (T) and parity (P) symmetry violation in molecules may also come from their nuclei. We point out that nuclear T, P-odd effects are amplified in paramagnetic molecules containing deformed nuclei, where the primary effects arise from the T, P-odd nuclear magnetic quadrupole moment (MQM). We perform calculations of T, P-odd effects in the molecules TaN, ThO, ThF+, HfF+, YbF, HgF, and BaF induced by MQMs. We compare our results with those for the diamagnetic TlF molecule, where the T, P-odd effects are produced by the nuclear Schiff moment. We argue that measurements in molecules with MQMs may provide improved limits on the strength of T, P-odd nuclear forces, on the proton, neutron, and quark EDMs, on quark chromo-EDMs, and on the QCD θ term and CP-violating quark interactions.

Topology of the interactions pattern in pharmaceutically relevant polymorphs of methylxanthines (caffeine, theobromine, and theophiline): combined experimental (¹H-¹⁴N nuclear quadrupole double resonance) and computational (DFT and Hirshfeld-based) study.

Three anhydrous methylxanthines: caffeine (1,3,7-trimethylxanthine; 1,3,7-trimethyl-1H-purine-2,6-(3H,7H)-dione) and its two metabolites theophylline (1,3-dimethylxanthine; 1,3-dimethyl-7H-purine-2,6-dione) and theobromine (3,7-dimethyl-xanthine; 3,7-dimethyl-7H-purine-2,6-dione), which reveal multifaceted therapeutic potential, have been studied experimentally in solid state by (1)H-(14)N NMR-NQR (nuclear magnetic resonance-nuclear quadrupole resonance) double resonance (NQDR). For each compound the complete NQR spectrum consisting of 12 lines was recorded. The multiplicity of NQR lines indicates the presence of a stable β form of anhydrous caffeine at 233 K and stable form II of anhydrous theobromine at 213 K. The assignment of signals detected in NQR experiment to particular nitrogen atoms was made on the basis of quantum chemistry calculations performed for monomer, cluster, and solid at the DFT/GGA/BLYP/DPD level. The shifts due to crystal packing interactions were evaluated, and the multiplets detected by NQR were assigned to N(9) in theobromine and N(1) and N(9) in caffeine. The ordering theobromine > theophylline > caffeine site and theophylline < theobromine < caffeine according to increasing electric field gradient (EFG) at the N(1) and N(7) sites, respectively, reflects the changes in biological activity profile of compounds from the methylxanthines series (different pharmacological effects). This difference is elucidated on the basis of the ability to form intra- and intermolecular interactions (hydrogen bonds and π···π stacking interactions). The introduction of methyl groups to xanthine restricts the ability of nitrogen atoms to participate in strong hydrogen bonds; as a result, the dominating effect shifts from hydrogen bond (theobromine) to π···π stacking (caffeine). Substantial differences in the intermolecular interactions in stable forms of methylxanthines differing in methylation (site or number) were analyzed within the Hirshfeld surface-based approach. The analysis of local environment of the nitrogen nucleus permitted drawing some conclusions on the nature of the interactions required for effective processes of recognition and binding of a given methylxanthine to A1-A(2A) receptor (target for caffeine in the brain). Although the interactions responsible for linking neighboring methylxanthines molecules in crystals and methylxanthines with targets in the human organism can differ significantly, the knowledge of the topology of interactions provides reliable preliminary information about the nature of this binding.

AFNMR/NQR signal enhancement via population transfer

Antiferromagnetic nuclear magnetic resonance (AFNMR) and nuclear quadrupole resonance (NQR) are useful techniques to characterize materials in bulk volumes without applying external static magnetic fields. For industrial materials characterization applications, it is crucial to maximize signal‐to‐noise ratio in the available time. We simulate the AFNMR and NQR signal enhancement via population transfer in single crystals and powders and predict the enhancement factors for half‐integer quadrupolar nuclei spin systems. Differences to conventional high‐field NMR population transfer experiments are emphasized. We restrict our discussion to electric field gradients with axial symmetry = 0. Triple resonance tuned crossed coil experiments on CuFeS2 and In2O3 powders support the numerical results. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part A 43A: 147–156, 2015.