High Pressure NQR Study of the Phase Transition in Anilinium Iodide

1986 ◽  
Vol 41 (1-2) ◽  
pp. 290-293
Author(s):  
Mariusz Maćkowiak ◽  
Maria Zdanowska-Fra̧zek ◽  
Piotr Kozioł ◽  
Jan Stankowski ◽  
Alarich Weiss
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Transition Temperature ◽  
Hydrogen Bonds ◽  
Transition Point ◽  
Pressure Coefficient ◽  
Coupling Constants ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Asymmetry Parameters

The 127I NQR frequency in anilinium iodide C6H5NH3⊕I⊖ was studied at pressures up to 300 MPa and within the temperature range 77 K - 290 K. With increasing pressure the order-disorder transition point Tc is shifted to higher temperatures. The pressure coefficient of the phase transition temperature amounts to dTc/dp = 4.2 x 10-2 deg MPa-1. The pressure coefficient of the NQR frequency is negative. In addition, the 12'I nuclear quadrupole coupling constants and the respective asymmetry parameters η were evaluated as a function of pressure. The results confirm the close connection between the mechanism of the phase transition and the dynamics of the N - H⊕ ...I⊖ hydrogen bonds.

14N and 39K Nuclear Quadrupole Coupüng in KNO3

1990 ◽  
Vol 45 (3-4) ◽  
pp. 459-463 ◽  
Author(s):  
T. J. Bastow ◽  
S. N. Stuart
Keyword(s):  
Phase Transition ◽  
Nuclear Magnetic Resonance ◽  
Room Temperature ◽  
Potassium Nitrate ◽  
Nuclear Quadrupole Interaction ◽  
Coupling Constants ◽  
Disorder Phase Transition ◽  
Nuclear Quadrupole ◽  
T Values ◽  
Asymmetry Parameters

Abstract The nuclear quadrupole interaction tensors of 14N and 39K in potassium nitrate at room temperature have been determined from nuclear magnetic resonance (NMR) rotation studies of single crystals at 9.4 T. Values for the coupling constants and asymmetry parameters at 296 K are:14N: e2 qQ/h = 751 kHz, η = 0.022; 39K: e2 qQ/h = 1326kHz, η = 0.171. The temperature dependence, on approaching the order-disorder phase transition near 401 K, is linear.

Theory of Nuclear Quadrupole Interactions of 14N, 17O, and 35Cl Nuclei in p-Cl-Ph-CH-N=TEMPO

2002 ◽  
Vol 57 (6-7) ◽  
pp. 527-531
Author(s):  
Junho Jeong ◽  
Tina M. Briere ◽  
N. Sahoo ◽  
T. P. Das ◽  
S. Ohira ◽  
...  
Keyword(s):  
Muon Spin ◽  
Hyperfine Interactions ◽  
Rotation Frequency ◽  
Coupling Constants ◽  
Muon Spin Rotation ◽  
Hartree Fock ◽  
Nuclear Quadrupole Interactions ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Asymmetry Parameters

The nuclear quadrupole coupling constants and asymmetry parameters have been studied for the 35Cl, 17O, and 14N nuclei in the molecular ferromagnet 4-(p-chlorobenzylideneamino)-TEMPO (2,2,6,6-tetramethyl- piperidin-1-yloxyl) using elctronic stuctures obtained by the Hartree-Fock procedure for the bare system and systems with trapped muon and muonium. Trends in the sizes of the coupling constants and asymmetry parameters for the various nuclei have been studied, and possible physical explanations have been proposed. For the systems with trapped muon or muonium, very substantial influences of the muon and muonium on the coupling constants and asymmetry parameters for the nuclei close to the trapping sites have been observed. The coupling constants and asymmetry parameters are found to be very different for the various nuclei, for the two cases where muon is trapped near chlorine and muonium near oxygen, indicating that, if experimental data were available to compare with theory, one could make conclusions about which of these two centers is responsible for the observed muon spin rotation frequency associated with the muon magnetic hyperfine interactions in these two trapped systems

NQR Studies of the Structure of Glasses and Crystalline Compounds

1992 ◽  
Vol 47 (1-2) ◽  
pp. 30-38 ◽  
Author(s):  
P. J. Bray ◽  
DongHoon Lee ◽  
De Gen Mao ◽  
G. L. Petersen ◽  
S. A. Feller ◽  
...  
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Borate Glasses ◽  
Low Frequencies ◽  
Structure Of Glasses ◽  
Quadrupole Coupling ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole ◽  
Asymmetry Parameters

AbstractPure nuclear quadrupole resonance (NQR) spectroscopy at low frequencies (down to 275 kHz) has been used to investigate a number of borate, aluminate, and vanadate crystalline compounds and borate glasses. The values of the quadrupole coupling constants (Qcc) and asymmetry parameters (η) are obtained with error limits that are one or two orders of magnitude less than those for values obtained from NMR spectra. New sites, not resolved in NMR spectra, have been detected for boron in borate glasses.

Preliminary Results of a 20 K X-Ray Study of Citrinin

1993 ◽  
Vol 48 (1-2) ◽  
pp. 99-104 ◽  
Author(s):  
R. Destro ◽  
F. Merati
Keyword(s):  
Dipole Moment ◽  
Hydrogen Bonds ◽  
Charge Density ◽  
Topological Analysis ◽  
Coupling Constants ◽  
Molecular Dipole ◽  
X Ray ◽  
A Value ◽  
Quadrupole Coupling ◽  
Asymmetry Parameters

Abstract A total of about 37 000 diffracted intensities has been measured at 20 K for a spherical single crystal of citrinin. Using a multipole formalism to interpret the X-ray data, maps of the charge density and of its Laplacian, as well as for the electrostatic potential have been derived. A value of 7(2) D has been obtained for the magnitude of the molecular dipole moment. A study of the electric field gradient (EFG) at the nuclei has yielded the atomic quadrupole coupling constants (QCC) and asymmetry parameters (η). A topological analysis of the charge density has been performed to characterize the intramolecular covalent and hydrogen bonds.

Nuclear Quadrupole Resonance of Antimony in Ln3Sb5O12 Crystals

1994 ◽  
Vol 49 (6) ◽  
pp. 687-689 ◽  
Author(s):  
A. M. Raevsky ◽  
A. G. Gukalova ◽  
G. K. Semin
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Coupling Constants ◽  
Spectral Parameters ◽  
Compression Effect ◽  
Quadrupole Coupling ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole ◽  
Asymmetry Parameters ◽  
Lanthanide Compression

Abstract Complete 121,123Sb NQR spectra of crystalline rate earth antimonites Ln3Sb5O12 (Ln = La, Nd, Er, Lu) were recorded at 77 K. The quadrupole coupling constants and asymmetry parameters of the electric field gradient were measured. A “lanthanide compression” effect on the antimony NQR was observed. Using relations found for the antimonites under study, the Sb spectral parameters of other lanthanide compounds can be predicted.

Quadrupoleffekte der magnetischen Kernresonanz an 11B in Bor-Stickstoffverbindungen

1969 ◽  
Vol 24 (4) ◽  
pp. 566-572 ◽  
Author(s):  
Klaus Wiedemann ◽  
Jürgen Voitländer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Quadrupole Interaction ◽  
Second Order ◽  
Coupling Constants ◽  
Quadrupole Coupling ◽  
Wide Line ◽  
Nuclear Quadrupole ◽  
Asymmetry Parameters ◽  
Nuclear Magnetic

Abstract First and second-order quadrupole effects of the 11B nuclear magnetic resonance have been measured in polycrystalline samples of dimere dimethylaminoboranes and tetramethylboracene. With the theory of powder patterns for first and second-order quadrupole interaction the nuclear quadrupole coupling constants e2 q Q/h and asymmetry parameters η of 11B have been determined. For these measurements boron-free inserts had to be constructed for the probes of the Varian Wide Line Spectrometer DA 60.

Sodium Ion Exchange in Na1+xZr2SixP3-xO12 as Studied by 23Na Nutation NMR

1992 ◽  
Vol 47 (1-2) ◽  
pp. 319-324 ◽  
Author(s):  
Hiroshi Ohki ◽  
Nobuo Nakamura
Keyword(s):  
Ion Exchange ◽  
Coupling Constants ◽  
Sodium Ion ◽  
Spectral Simulation ◽  
Quadrupole Coupling ◽  
Significant Temperature ◽  
Nuclear Quadrupole ◽  
Fast Ion ◽  
Two Peaks ◽  
Asymmetry Parameters

Abstract 23Na two-dimensional nutation NMR was applied to Na1+x* Zr2SxP3-xO12 with x = 0, 1, and 2. The nutation spectrum in each compound consists of two clearly separated peaks corresponding to the two crystallographically inequivalent sodium sites. In the compound with x = 2 the nuclear quadrupole coupling constants (e2 Qq/h) and the asymmetry parameters (η) were by spectral simulation estimated to be 1.0 MHz and 0 for one site, and 1.5 MHz and 0.8 for the other site. The spectrum varies considerably on heating; the two peaks merge into a single peak at high temperatures due to fast ion exchange between the two different sites. For x = 0 and x = 1 the nutation spectra did not show any significant temperature dependence, suggesting that the rates of the sodium ion exchange are negligibly low.

The chemical interpretation and the temperature dependence of the 14N nuclear quadrupole resonance of aniline and several derivatives

1968 ◽  
Vol 46 (22) ◽  
pp. 3595-3604 ◽  
Author(s):  
C. T. Yim ◽  
M. A. Whitehead ◽  
Donald H. Lo
Keyword(s):  
Temperature Dependence ◽  
Nuclear Quadrupole Resonance ◽  
Coupling Constants ◽  
Temperature Range ◽  
Resonance Frequencies ◽  
Quadrupole Coupling ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole ◽  
Asymmetry Parameters ◽  
Phenylene Diamine

The 14N nuclear quadrupole resonance frequencies of aniline, o- and p-phenylene diamine, and p-chloro-, p-bromo-, and p-iodo-aniline were measured with a super-regenerative oscillator over a temperature range from 77 to 292 °K. The temperature dependence is analyzed. The chemical interpretation of the quadrupole coupling constants and asymmetry parameters is described.

Weakly Coordinating Ligands: Nuclear Quadrupole Coupling Constants and Asymmetry Parameters of Iodocarbons Coordinated to Metal Ions

2000 ◽  
Vol 55 (1-2) ◽  
pp. 145-150 ◽  
Author(s):  
Gary Wulfsberg ◽  
Joyce Robertson ◽  
T. A. Babushkina ◽  
S. I. Gushchin ◽  
Hiromitsu Terao ◽  
...  
Keyword(s):  
Low Frequency ◽  
Silver Ions ◽  
Coupling Constants ◽  
Resonance Spectroscopy ◽  
Electronic Interaction ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Weakly Coordinating ◽  
First Time ◽  
Asymmetry Parameters

NQR (nuclear quadrupole resonance) spectroscopy is potentially one of the best ways of characterizing the bonding of metal cations such as zirconocene cations and Ag+ to halogen donor atoms in weakly coordinating anions and neutral ligands such as halocarbons. Known coordination of organoiodine atoms to silver ions was studied by 127I NQR spectroscopy in [Ag(p-C6H4I2)](PO2F2), [Ag(o-C6H4I2)]N03 , [Ag(CH2I2)2]PF6, and the explosive [Ag(CH2I2)]NO3 ; a possible case of iodocarbon coordination to a mercury atom in C5Cl5HgCl ·CH2I2 was also investigated. Both the low-frequency (ca. 300 MHz) and the high-frequency (ca. 500 MHz) NQR signals were detected for each compound, and, for the first time, the quadrupole coupling constants e2Qqzz/h and asymmetry parameters ηof coordinated organohalogen atoms were obtained. As compared to the free iodocarbons, substantial (4 - 12%) reductions of e2Qqzz/h and substantial increases in η (to about 20 - 40%) were found in the iodocarbon complexes of silver, but not of mercury. From approximate theoretical analysis of the data, it appears that the electronic interaction of silver and iodine is quite substantial.

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