The asymmetry parameter of the deuteron quadrupole coupling constant in aromatic molecules; σ-π inequivalence

1974 ◽  
Vol 27 (3) ◽  
pp. 605-609 ◽  
Author(s):  
Richard Bersohn
Keyword(s):  
Asymmetry Parameter ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Aromatic Molecules ◽  
Quadrupole Coupling ◽  
The Asymmetry

scholarly journals Two-Dimensional Nutation NQR Broad-Line Spectra in Oriented Samples

2006 ◽  
Vol 61 (9) ◽  
pp. 499-504 ◽  
Author(s):  
Nicolay Sinyavsky ◽  
Irina Korneva ◽  
Michał Ostafin ◽  
Bolesław Nogaj ◽  
Mariusz Maćkowiak
Keyword(s):  
Asymmetry Parameter ◽  
Disordered Systems ◽  
Quadrupole Coupling Constant ◽  
Two Dimensional ◽  
Coupling Constant ◽  
Nuclear Spins ◽  
Radio Frequency Field ◽  
Quadrupole Coupling ◽  
Oriented Samples ◽  
Constant E

The NQR nutation method to determine the electric field gradient asymmetry parameter η in systems, where the resonance line is so broad that the radio frequency field can excite only a portion of the nuclear spins, is presented. In this situation, the recently developed spectroscopic methods are not applicable. Two-dimensional nutation NQR spectra of oriented powders are calculated and used to determine η at particular frequencies along a broad NQR line. The proposed method is useful for single crystals, oriented powders, glasses, and disordered systems even for small values of the asymmetry parameter. Therefore it can be used to evaluate fluctuations in η and the quadrupole coupling constant e2qQ due to inhomogeneities. We demonstrate the application of this method to oriented chalcogenide semiconducting glasses.

Pulsed nuclear magnetic resonance study of deuteron lineshapes in clathrate hydrates

1977 ◽  
Vol 55 (1) ◽  
pp. 78-81 ◽  
Author(s):  
John A. Ripmeester
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Asymmetry Parameter ◽  
Quadrupole Coupling Constant ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constant ◽  
Magnetic Resonance Study ◽  
Guest Molecules ◽  
Quadrupole Coupling ◽  
Line Characteristic ◽  
Pulsed Nuclear Magnetic Resonance

D nmr lineshape information was obtained from the echo response following a pair of phase shifted pulses using a method first proposed by Clark. In this manner the D quadrupole coupling constant and asymmetry parameter for D2O in p-dioxane•17D2O were found to be 217 kHz and 0.10 at 63 K. The D nmr lineshape for ethylene oxide-d4•7H2O shows that at 17 K the guest molecules are held rigidly in their cages. At higher temperatures the doublet lineshape collapses to a broad structureless line characteristic of molecules for which the reorientational modes vary from cage to cage.

Hydrogen Bond Studies

1977 ◽  
Vol 32 (2) ◽  
pp. 134-139 ◽  
Author(s):  
Bo Berglund ◽  
Jörgen Tegenfeldt
Keyword(s):  
Asymmetry Parameter ◽  
Room Temperature ◽  
Sodium Perchlorate ◽  
Quadrupole Coupling Constant ◽  
Water Molecules ◽  
Coupling Constant ◽  
Nmr Spectrum ◽  
Quadrupole Coupling ◽  
Constant E ◽  
The Difference

The quadrupole splittings in the deuterium NMR spectrum from single crystals of deuterated sodium Perchlorate monohydrate, NaClO4-D2O, have been measured at 25 °C and - 55 °C. At room temperature, the 180° flip frequency of the D2O molecules is large compared to the difference between the splittings for the two deuterons. The average quadrupole coupling constant (e2 q Q/h) and asymmetry parameter η are 134.1(4) kHz and 0.621(5), respectively. At -55 °C, the electric field gradient tensors for each of the two deuterons were observed corresponding to slowly flipping water molecules, and e2 qQ/h and η for the two deuterons are 231.5(6) and 226.7(6) kHz and 0.196(4) and 0.195(5), respectively. The results indicate that the hydrogen positions in NaClO4-H2O are dynamically disordered

Powder Zeeman NQR Study on 123Sb in Sb(C6H5)3

2002 ◽  
Vol 57 (6-7) ◽  
pp. 304-306
Author(s):  
O. Ege ◽  
S. Maekawa ◽  
H. Negita
Keyword(s):  
Computer Simulation ◽  
Line Shape ◽  
Asymmetry Parameter ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Line Shapes ◽  
Quadrupole Coupling ◽  
Saddle Type ◽  
Lower Series ◽  
Good Agreement

Powder Zeeman NQR spectra of 123Sb in Sb(C6H5)3 were studied by means of a computer simulation and an experiment. The 123Sb nucleus has spin 7/2. There are two non-equivalent 123Sb atoms in the crystal of Sb(C6H5)3, so that there are two series of three transition lines (higher series: ν1h, ν2h, ν3h; lower series: ν11, ν21, v31). The powder Zeeman spectra for ν1h, based on the transition between the levels mI = ±1/2 and ±3/2, were observed at 77 K under the two conditions that i) the oscillation coil and the static magnetic coil were set coaxially and parallel, and ii) they were set perpendicular to each other. The powder line shapes for ν1h, which is the lowest line of the higher series due to 123Sb nuclei, were in good agreement with those from a computer simulation under the conditions i) and ii), showing that the asymmetry parameter of the field gradient is very small (η = 0). The line shape from i) exhibits two shoulders (saddle type), as it appeared for nuclear spin 5/2 and η = 0. The quadrupole coupling constant for 1h, calculated from the resonance frequency 47.820 MHz and the observed η, is 669.480 MHz at 77 K.

Die Temperaturabhängigkeit der Kernquadrupolkopplungskonstante von Na23 in Natriumnitrit, NaNO2

1962 ◽  
Vol 17 (9) ◽  
pp. 794-798 ◽  
Author(s):  
Alarich Weiss ◽  
D. Biedenkapp
Keyword(s):  
Asymmetry Parameter ◽  
Transition Point ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Point Charge Model ◽  
Nuclear Quadrupole Coupling Constant ◽  
Charge Model ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Increasing Temperature

The nuclear quadrupole coupling constant of Na23 in sodium nitrite. NaNO2. has been investigated between 18 °C and 215 °C. Below the transition temperature (163 ± 2)°C the asymmetry parameter η= (φxx — φyy)/φzz decreases with increasing temperature and goes to zero at the transition point. Above 163 °C η is negative and | η | increases with temperature. This temperature dependence of the nuclear quadrupole coupling cannot be explained adequately by the point charge model together with the assumption of the free rotation of the NO2-group above the transition point.

Temperature Dependence of 14N NQR and Phase Transitions in KNO2 Powder

1996 ◽  
Vol 51 (5-6) ◽  
pp. 769-772 ◽  
Author(s):  
Hae Jin Kim ◽  
Kee Tae Han ◽  
Sung Ho Choh
Keyword(s):  
Phase Transitions ◽  
Temperature Dependence ◽  
Asymmetry Parameter ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Nuclear Quadrupole Coupling Constant ◽  
Quadrupole Coupling ◽  
Two Temperatures ◽  
Nuclear Quadrupole

Abstract The temperature dependence of 14N NQR, measured at 77 to 300 K, is in better agreement with the model proposed by Blinc et al. than the Bayer theory. The nuclear quadrupole coupling constant and asymmetry parameter show a discontinuity at about 160 K and 230 K, respectively. The linewidths are broadened at these temperatures up to 22 kHz and 18 kHz, respectively. These results indicate that KNO2 undergoes phase transitions at these two temperatures.

Distribution of Electric Field Gradient at Aluminum Sites in Zeolite Loaded with Potassium

2002 ◽  
Vol 57 (6-7) ◽  
pp. 495-498 ◽  
Author(s):  
M. Igarashi
Keyword(s):  
External Field ◽  
Asymmetry Parameter ◽  
Quadrupole Coupling Constant ◽  
Central Line ◽  
Coupling Constant ◽  
First Order ◽  
Nuclear Quadrupole Coupling Constant ◽  
Quadrupole Coupling ◽  
Zeolite Lta ◽  
Nuclear Quadrupole

In the zeolite LTA, loaded with potassium, the temperature and field dependence of 27Al NQR was observed. Symmetrical single shoulders are found on both sides of the central line. The shape and the shift of those shoulders show no dependence on both temperature and the strength of the external field. This evidences a first order electric quadrupolar shift, being the result of the distribution of the nuclear quadrupole coupling constant and the asymmetry parameter at 27Al sites

Dynamics of Water in Crystal Hydrates

1967 ◽  
Vol 22 (9) ◽  
pp. 1452-1457 ◽  
Author(s):  
S. Ketudat ◽  
I. Berthold ◽  
Alarich Weiss
Keyword(s):  
Activation Energy ◽  
Water Molecule ◽  
Asymmetry Parameter ◽  
Room Temperature ◽  
Structural Parameters ◽  
Quadrupole Coupling Constant ◽  
The Other ◽  
Coupling Constant ◽  
Kcal Mole ◽  
Quadrupole Coupling

Deuteron magnetic resonance in Na2S2O6 · 2 D2O single crystals was investigated in the temperature range —68°C to +80°C. The activation energy for the flipping motion of the heavy water molecule was found to be (9.2 ± 1.5) kcal/mole. The quadrupole coupling constant and the asymmetry parameter in the low temperature case was found to be e2 q Q/h= (244 ± 3) kHz, η = 0.103 ± 0.003 for gne deuteron and e q Q/h = (236 ± 3) kHz, η=0.116 ± 0.003 for the other deuteron of the same water molecule. For the fast flipping case at room temperature e2 q Q/h= (131 ± 2) kHz and η=0.77 ± 0.02. Good agreements in structural parameters of the water molecule of Na2S2O6 · 2 D2O and of Na2S2O6 · 2 H2O were found.

Nuclear Quadrupole Interactions of 27Al in Alexandrite Single Crystal

1998 ◽  
Vol 53 (6-7) ◽  
pp. 568-572 ◽  
Author(s):  
T. H. Yeom ◽  
S. H. Choh ◽  
K. S. Hong ◽  
H. Y. Yeom ◽  
Y. H. Park ◽  
...  
Keyword(s):  
Single Crystal ◽  
Asymmetry Parameter ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Experimental Accuracy ◽  
Quadrupole Interactions ◽  
Nuclear Quadrupole Interactions ◽  
Nuclear Quadrupole Coupling Constant ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

Abstract In an alexandrite single crystal four sets of NMR spectra for 27Al (I=5/2) were observed in the crystallographic ab, be, and ca planes. The AI (I) center has four magnetically inequivalent Al sites, whereas the AI (II) center has two. The nuclear quadrupole coupling constant and asymmetry parameter of Al(I) and AI(II) in an alexandrite crystal were determined. Within the experimental accuracy, our parameters turned out to have the same values as those of a chrysoberyl crystal.

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