Study of the modifications of the electric field gradient in hexafluorohafnates of transition metals above room temperature

1993 ◽  
Vol 77 (1) ◽  
pp. 93-101 ◽  
Author(s):  
M. A. Taylor ◽  
M. Ceolín ◽  
J. A. Martínez
Keyword(s):  
Transition Metals ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Room Temperature

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

Lattice Locations of 12B in CaB6

2002 ◽  
Vol 57 (6-7) ◽  
pp. 617-619 ◽  
Author(s):  
M. Mihara ◽  
K. Hashimoto ◽  
K. Arimura ◽  
S. Kudo ◽  
K. Akutsu ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Quadrupole Interaction ◽  
Room Temperature ◽  
Nuclear Quadrupole Interaction ◽  
Nmr Studies ◽  
Nuclear Quadrupole ◽  
Lattice Locations ◽  
La Doped

The nuclear quadrupole interaction of the short-lived -emitter 12B implanted into CaB6 crystal has been studied by means of modified β-NMR (β-NQR) technique. The electric field gradient at the implanted 12B was found to be = q-(1.34±0.05)x1021 V/m2 at room temperature. From this result it is concluded that the 12B probe nuclei are mainly implanted in the substitutional boron site and are applicable to systematic NMR studies of ferromagnetic La doped CaB6

scholarly journals Electric field gradient at the 111Cd(←111In) site in Ga-doped ZnO

2011 ◽  
Vol 1 (1) ◽  
pp. 435-438 ◽  
Author(s):  
W. Sato ◽  
Y. Ohkubo ◽  
Y. Itsuki ◽  
S. Komatsuda ◽  
D. Minami ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Room Temperature ◽  
Local Environment ◽  
Relative Width ◽  
Probe Nucleus ◽  
Tdpac Spectrum ◽  
Time Differential ◽  
Doped Zno

AbstractThe time-differential perturbed angular correlation (TDPAC) method was applied to a study of the local environment at the 111Cd(←111In) probe nucleus introduced in 0.5 at. % Ga-doped ZnO. The TDPAC spectrum obtained at room temperature suggests that the doped Ga ions reside at the substitutional Zn site and they are locally associated in immediate proximity to the probe, reflecting strong attractive force between the probe and the dopants. The relative width of the magnitude of the electric field gradient produced at the probe nucleus shows that the doped Ga ion(s) adjacent to the probe is/are diversely distributed compared with doped In ion(s).

Article

1999 ◽  
Vol 77 (11) ◽  
pp. 1973-1983
Author(s):  
Robert W Schurko ◽  
Roderick E Wasylishen ◽  
Scott J Moore ◽  
Luigi G Marzilli ◽  
John H Nelson
Keyword(s):  
Solid State ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Nmr Spectra ◽  
Room Temperature ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Magic Angle ◽  
Spin Spin Coupling

Solid-state 31P NMR spectra of two phosphite- and 17 phosphine-substituted cobaloximes have been acquired under conditions of magic-angle spinning (MAS) and cross polarization (CP) at two applied magnetic fields. In the majority of cases, eight-peak multiplets are observed in the 31P CPMAS NMR spectra, arising from one-bond indirect spin-spin coupling to cobalt (spin S = 7/2). The spacings between adjacent peaks gradually increase or decrease from low to high frequency, due to the presence of residual dipolar coupling between the cobalt and phosphorus nuclei. Values of 1J(59Co,31P) were estimated from the spacing between the central peaks of the eight-peak multiplets. For the phosphine-substituted cobaloximes, values of 1J(59Co,31P) range from 225 to 372 Hz, while in the phosphite derivatives this coupling is considerably larger, from 420 to 615 Hz. From comparison with cobaloximes for which the cobalt nuclear quadrupole coupling interaction is fully characterized, the residual dipolar shift, d, and sense of the 31P NMR spectrum can be utilized to infer the electric field gradient (EFG) orientations at the cobalt nucleus in cobaloximes for which such data are unavailable. The magnitudes of 1J(59Co,31P) and d, as well as the sense of the spectra, are shown to be dependent upon the nature of the axially-substituted ligands. Phosphorus-31 CPMAS NMR spectra of several cobaloximes exhibit broad peak shapes at room temperature. Variable-temperature 31P NMR experiments reveal that the cobalt nucleus is effectively self-decoupled at room temperature; however, splittings due to 1J(59Co,31P) were observed in spectra acquired at low temperatures.Key words: solid-state 31P NMR, 59Co-31P spin-spin coupling constants, 59Co electric field gradient tensors, cobaloximes.

Electric field gradient in pure hexagonal transition metals

1977 ◽  
Vol 5 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Michel Piecuch ◽  
Christian Janot
Keyword(s):  
Transition Metals ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient
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