Electric-charge redistribution in the HCl subunit of hydrogen-bonded dimers B • • • HC1 from Cl nuclear quadrupole coupling: determination of the coefficient F zz of the electric-field-induced field gradient in HCl

1988 ◽  
Vol 417 (1852) ◽  
pp. 21-30 ◽  
Keyword(s):  
Electric Field ◽  
Field Gradient ◽  
Zero Point ◽  
Coupling Constants ◽  
Dimer Formation ◽  
Quadrupole Coupling ◽  
Electrical Effect ◽  
Induced Field ◽  
Nuclear Quadrupole

An interpretation is given of the chlorine nuclear quadrupole coupling constants X (Cl) for the series of dimers B • • • HCl and B • • • DCl where B = CO, C 2 H 4 , C 2 H 2 , PH 3 , H 2 S, HCN, CH 3 CN, H 2 O and NH 3 . The factors that contribute to the change in X (Cl) on dimer formation are considered in turn. First, account is taken of the effect of bond lengthening of the HCl subunit that occurs on dimer formation. Secondly, the contribution X E to the change in the coupling constant that arises from the electrical effect of B on the field gradient at the Cl nucleus in the dimer is treated at equilibrium in terms of two contributions according to the equation X E = X P + X Q = ‒ eQ {F zz F z + G zz F zz }/ h . The first term X P results from the polarization of the HCl subunit by the electric field F z due to B. The second term X Q arises from the field gradient F zz due to B but modified by the factor (l + γ zz ) = G zz , where γ zz is the usual Sternheimer antishielding factor. F zz is the corresponding factor associated with the field gradient at the Cl nucleus resulting from the polarization of the HCl subunit by the field due to B. The term X Q is directly evaluated using an available Sternheimer antishielding factor. Thirdly, allowance is made for the effect of averaging over the zero-point bending motion of the dimer. Finally, the remaining term X P has then been calculated for each member of the series B • • • HC1 and shown to be linearly dependent on F z as required by the above expression. Hence it has been possible for the first time to make an experimental determination of an F zz value of a gas-phase molecule and we report F zz = ‒116(6) x 10 10 m -1 for the HCl molecule.

Weak Complexes of Dinitrogen: An Approach to the 14N-Nuclear Quadrupole Coupling Constant of Free N2

1992 ◽  
Vol 47 (1-2) ◽  
pp. 367-370 ◽  
Author(s):  
A. C. Legon ◽  
P. W. Fowler
Keyword(s):  
Ground States ◽  
Zero Point ◽  
Quadrupole Coupling Constant ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Nuclear Quadrupole Coupling Constant ◽  
Quadrupole Coupling ◽  
Weak Complexes ◽  
Nuclear Quadrupole

AbstractThe 14N-nuclear quadrupole coupling constants χaa(14N<2>) and χaa(14N(1)) for the ground-states of the dimers 14N(2)14N(1) • • • HCCH and 14N(2)14N(1) • • • HC15N have been corrected for zero-point effects and for the electrical effects of the subunit HX to give two estimatesχ(14N) = -5.01 (13) and - 5.07 (8) MHz, respectively, for the coupling constant of the isolated 14N2 molecule

The Electric Field Gradient at the Site of the Halogen Ion and Structure of Amino Acid Hydrobromides and Hydroiodides

1992 ◽  
Vol 47 (7-8) ◽  
pp. 887-917
Author(s):  
Armin Kehrer ◽  
Shi-qi Dou ◽  
Alarieh Weiss
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Room Temperature ◽  
Low Frequency ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Resonance Frequencies ◽  
Quadrupole Coupling ◽  
Frequency Coupling

Abstract The 79,81Br and 127I NQR spectra of several hydrobromides, respectively hydroiodides, of amino acides and dipeptides were studied, mostly as functions of temperature in the range 77 < T/K <420. The investigated compounds are: L-Arg • HBr • H2O, L-Cys • HBr • H2O , L - Cys - S - S - L - Cys • 2HBr, ethanolamine • HBr, L-Glu • HBr, L-His • HBr, L-His • 2HBr, L-Ile HBr • H2O , Sar • HBr, (Sar)2 • HBr, L-Val • HBr • H2O , Gly • LiBr, Gly-Gly • LiBr, ethanolamine HI, Sar • HI, (Sar)2 • HI, (Gly)2 • HI, (L-Val)2 • HI, Gly-L-Leu • HI • H2O . A phase transition with hysteresis was observed for L-Val • HBr • H2O (Tc.up = 318 K, Tc.down = 242 K). Two solid phases of Sar • HI have been studied by NQR, one crystallized from melt, the other one from aqueous solution. For three of the title compounds the crystal structure was determined at room temperature: L-His - 2HBr, P212121 , Z = 4, aj pm = 1652, b/pm = 916, c/pm = 721; L-Cys HBr H2O , P212121 , Z = 4, a/pm = 1955, b/pm = 746, c/pm = 550; Gly-L-Leu • HI • H2O , P2X, Z = 2, a / p m = 1289, b/pm = 914, c/pm = 615, ß/° = 99.In most cases the halogen ion in the studied hydrohalides is polycoordinated by hydrogen bonds of the type N - H • • • X⊖ and O - H • • • X⊖ , X = Br, I. The NQR frequencies and, for iodine, the nuclear quadrupole coupling constants depend on this coordination. A low frequency (coupling constant) region is found for pure N - H • • • X⊖ coordination. Replacing one N - H • • • X⊖ bond by O - H • • • X⊖ rises the electric field gradient, EFG, respectively the resonance frequencies. The dependence of the EFG on the hydrogen bond coordination N - H • • • X⊖ plus O - H • • • X⊖ is discussed for the title compounds including information from literature

Determination of the Sign of Nuclear Quadrupole Interaction by Laser-Radiofrequency Double-Resonance Determination of the Sign of Nuclear Quadrupole Interaction by Laser-Radiofrequency Double-Resonance

1994 ◽  
Vol 49 (1-2) ◽  
pp. 14-18
Author(s):  
Tilo Blasberg ◽  
Dieter Suter
Keyword(s):  
Quadrupole Interaction ◽  
Double Resonance ◽  
High Sensitivity ◽  
Quadrupole Coupling Constant ◽  
Nuclear Quadrupole Interaction ◽  
Coupling Constants ◽  
Quadrupole Coupling ◽  
New Type ◽  
Nuclear Quadrupole

Abstract We describe a new type of laser-radiofrequency double-resonance experiment, which allows to determine not only the absolute value but also the sign of nuclear quadrupole coupling constants. This determination of the sign, which is essential for the comparison with calculated EFG tensors, is not possible with purely magnetic experiments. The m ethod has a high resolution and, because of the optical detection, also a high sensitivity. As an example, the quadrupole coupling constant for Pr3+ :YAlO3 was measured at 4.38 K and was found to be negative.

Electric Field Nuclear Magnetic Resonance (Application to Nuclear Quadrupole Coupling)

1986 ◽  
Vol 41 (1-2) ◽  
pp. 421-424 ◽  
Author(s):  
B. H. Ruessink ◽  
C. MacLean
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Electric Field ◽  
Experimental Method ◽  
Theoretical Approach ◽  
Liquid State ◽  
Experimental Results ◽  
Coupling Constants ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

The technique of electric field NMR is outlined in terms of theoretical approach and of experimental method. As an illustration, new and recent values for quadrupole coupling constants measured in the liquid state are reported. They are compiled together with observations from the solid and the gas. A discussion concerning the differences between the phases is briefly given. Experimental results of quadrupole coupling constants for all of the three phases are still scarce.

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.

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