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

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.

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Hydrogen Bond Studies

Zeitschrift für Naturforschung A ◽

10.1515/zna-1977-0206 ◽

1977 ◽

Vol 32 (2) ◽

pp. 134-139 ◽

Cited By ~ 1

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

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Electric Quadrupole Moment of the 14N Nucleus Determined by ab initio Cl Calculation on NH3

Zeitschrift für Naturforschung A ◽

10.1515/zna-1986-1-223 ◽

1986 ◽

Vol 41 (1-2) ◽

pp. 163-165 ◽

Cited By ~ 1

Author(s):

Tae-Kyu Ha

Keyword(s):

Electric Field Gradient ◽

Ab Initio ◽

Electric Quadrupole ◽

Quadrupole Coupling Constant ◽

Basis Set ◽

Electric Quadrupole Moment ◽

Coupling Constant ◽

Hartree Fock ◽

Quadrupole Coupling ◽

Constant E

Based on the calculated electric field gradient (q) from ab initio Cl wavefunctions with largebasis set (including ƒ functions on N and d functions on H) and the experimental nuclearquadrupole coupling constant (e Q q) for nitrogen in NH3, an improved value o f the quadrupole moment of 14N is proposed as Q (14N ) = 2.08 x 10-26cm2. The value calculated using a wavefunctionnear the Hartree-Fock limit enlarged ≈ 10% by the Cl treatment.

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Studies of Successive Phase Transitions and Molecular Motions in [Mg(H2O)6][SiF6] by 1,2H and 19F NMR

Zeitschrift für Naturforschung A ◽

10.1515/zna-1998-6-728 ◽

1998 ◽

Vol 53 (6-7) ◽

pp. 453-458 ◽

Cited By ~ 7

Author(s):

Junko Kimura ◽

Takeshi Fukase ◽

Motohiro Mizuno ◽

Masahiko Suhara

Keyword(s):

Phase Transitions ◽

Nmr Spectra ◽

Quadrupole Coupling Constant ◽

Coupling Constant ◽

Molecular Motions ◽

Exponential Factor ◽

H Nmr ◽

Quadrupole Coupling ◽

Constant E ◽

Successive Phase

Abstract The successive phase transitions of [Mg(H2O)6][SiF6] were studied by measuring 2H NMR spectra. The quadrupole coupling constant e2Qq/h and asymmetry parameter η changed drastically at each transition temperature. 1,2H and 19F NMR Tl were measured for this compound to study the relation between the molecular motions and the successive phase transitions. The activation energy Ea and the pre-exponential factor τ0 for the reorientation of [SiF6]2- were estimated as 28 kJmol-1 and 6.0 x 10-14 s, and those of the 180° flip of H2O as 33 kJmol-1 and 4.0x 10-14 s. These two motions occur rapidly even in phase V. For the reorientation of [Mg(H2O)6]2+ , Ea = 62 kJmol-1 and τ0 = 1.1 x 10-16 s were obtained from the simulation of 2H NMR spectra. The jump rate of this motion is of the order of 104 -106 s-1 in phase II. These results suggest that the successive phase transitions are closely related to the motion of [Mg(H2O)6]2+ .

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High Resolution and Solid State NMR Investigations of Subvalent Gallium Compounds

Zeitschrift für Naturforschung A ◽

10.1515/zna-1986-1-258 ◽

1986 ◽

Vol 41 (1-2) ◽

pp. 315-318 ◽

Cited By ~ 11

Author(s):

Hubert Schmidbaur ◽

Theodore Zafiropoulos ◽

Wolfgang Bublak ◽

Paul Burkert ◽

Frank H. Köhler

Keyword(s):

Solid State ◽

Nmr Spectra ◽

Quadrupole Coupling Constant ◽

Coupling Constant ◽

Gallium Atom ◽

Line Shapes ◽

Quadrupole Coupling ◽

Structure Determinations ◽

Constant E ◽

Gallium Compounds

The 71Ga NMR spectra of Ga[GaX4] melts and of solutions in benzene and other hydrocarbons show discrete sharp GaI and broad GaIII resonances. In the light of recent structure determinations, the solution GaI signals must be attributed to bis(arene)Ga+ complexes in which the gallium atom is η6-bonded to the hydrocarbons. The low line widths and strong high field shifts are attributed to an almost spherical shielding of the metal nucleus by the 4 s2 electrons. Solid state 69Ga and 71Ga NMR spectra of Ga[GaCl4] crystalline powder show only Ga1 resonances. While the 71GaI line is rather narrow, the 69GaI line has a complex fine structure. Consistent with the crystal structure of Ga[GaCl4], the Ga1 ion is calculated to have a very low quadrupole coupling constant e2q Q/h = 1.7 ± 0.1 MHz and an asymmetry parameter η = 0.44. Experimental and simulated line shapes (using literature models) are in satisfactory agreement, implying that the 69Ga signal splitting is due to second order quadrupolar effects for the central m = + 1/2 ⇋ - 1/2 transition. The analogous splitting of the 71Ga NMR line is too small to be detected.

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Pulsed nuclear magnetic resonance study of deuteron lineshapes in clathrate hydrates

Canadian Journal of Chemistry ◽

10.1139/v77-014 ◽

1977 ◽

Vol 55 (1) ◽

pp. 78-81 ◽

Cited By ~ 14

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.

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

Zeitschrift für Naturforschung A ◽

10.1515/zna-2002-6-703 ◽

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.

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The Temperature Dependence of 121,123Sb, 35Cl, 79,81Br and 127I NQR Spectra in Complexes Cs3Sb2X9 (X = Cl, Br, I)

Zeitschrift für Naturforschung A ◽

10.1515/zna-2000-1-223 ◽

2000 ◽

Vol 55 (1-2) ◽

pp. 134-138 ◽

Cited By ~ 4

Author(s):

L. A. Zemnukhova ◽

S. I. Kuznetsov ◽

G. A. Fedorishcheva ◽

R. L. Davidovich

Keyword(s):

Electric Field ◽

Aqueous Solutions ◽

Electric Field Gradient ◽

Temperature Dependence ◽

Quadrupole Coupling Constant ◽

Coupling Constant ◽

Quadrupole Transition ◽

Quadrupole Coupling ◽

Coeffi Cients ◽

Constant E

The 123,123Sb, 35Cl, 79,81Br and 127I NQR Spectra of the complexes Cs3Sb2X9 (X = Cl, Br, I), prepared from CsX and SbX3 aqueous solutions, were studied at 77-400 K. Analysis of the^ temperature coeffi-cients of the quadrupole transition frequency (v), quadrupole coupling constant (e2Qqzz) and asymme-try parameter of the electric field gradient (η) was carried out.

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ß-NMR Study of the Electric Field Gradient in the Metallic Intercalation Compound LiC6

Zeitschrift für Naturforschung A ◽

10.1515/zna-1986-1-215 ◽

1986 ◽

Vol 41 (1-2) ◽

pp. 109-112 ◽

Cited By ~ 6

Author(s):

P. Freiländer ◽

P. Heitjans ◽

H. Ackermann ◽

B. Bader ◽

G. Kiese ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Intercalation Compound ◽

Quadrupole Coupling Constant ◽

Layered Compound ◽

Thermal Neutrons ◽

Coupling Constant ◽

Nmr Study ◽

Nuclear Magnetic Resonance Spectra ◽

Quadrupole Coupling ◽

Constant E

In the layered compound LiC6polarized β-active 8Li probe nuclei were produced by captureof polarized thermal neutrons. Nuclear magnetic resonance spectra of 8Li were recorded via theβ-radiation asymmetry. The 8Li quadrupole coupling constant e2qQ/h , measured in the temperature range T = 5 . .. 500 K decreases with increasing 7 from 45.2(8) to 22.8(4) kHz.Anomalies in the overall temperature dependence are discussed in terms of phase transitionsproposed for LiC6.

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Die Temperaturabhängigkeit der Kernquadrupolkopplungskonstante von Na23 in Natriumnitrit, NaNO2

Zeitschrift für Naturforschung A ◽

10.1515/zna-1962-0909 ◽

1962 ◽

Vol 17 (9) ◽

pp. 794-798 ◽

Cited By ~ 20

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.

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79,81Br−127I−NQR, and Crystal Structure of Glycyl-l-alanine Hydrobromide Monohydrate and Hydroiodide Monohydrate

Zeitschrift für Naturforschung A ◽

10.1515/zna-1989-0710 ◽

1989 ◽

Vol 44 (7) ◽

pp. 659-668 ◽

Cited By ~ 1

Author(s):

Armin Kehrer ◽

Shi-qi Dou ◽

Alarich Weiss

Keyword(s):

Crystal Structure ◽

Hydrogen Bonds ◽

Room Temperature ◽

Quadrupole Coupling Constant ◽

Coupling Constant ◽

Lattice Constants ◽

Nuclear Quadrupole Coupling Constant ◽

Quadrupole Coupling ◽

Constant E ◽

Nuclear Quadrupole

Abstract The crystal structures of glycyl-l-alanine hydrobromide monohydrate, 1, and glycyl-l-alanine hydroiodide monohydrate, 2, were determined and the temperature dependence of the 127I NQR frequencies was investigated in the temperature range 77 <̳T/K <̳ 370. The 127I NQR frequencies are strongly influenced by hydrogen bonds and this is proved by the frequency shift of the H ⇄ D exchange. By deuteration the nuclear quadrupole coupling constant e2 qQh−1(127I) of 2 is shifted downwards 2.72 MHz at room temperature. The title compounds are isotype, and at room temperature they crystallize monoclinic with the space group C22 − P21 with two molecules in the unit cell. The lattice constants for 1 are a = 1068.7 pm, b = 614.1 pm, c = 762.0 pm, and β= 108.55° and for 2 are a = 1093.3 pm, 6 = 637.1 pm, c = 770.9 pm, and β= 107.29°.

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