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1998 (3)
1993 (1)
1Author    G. J. Hill, J. M. Keartland, M.J R HochRequires cookie*
 Title    Pressure Dependence of the EFG in Semimetallic Arsenic and Antimony  
 Abstract    The pressure variation of the axial EFG at the ion sites in semimetallic arsenic and antimony, at am-bient temperature, has been investigated using pulsed NQR. A weakly nonlinear decrease of the EFG is observed in both systems. The data are analyzed in terms of the lattice contribution to the EFG, which involves a lattice of point monopoles immersed in a uniform, compensating, background charge. The pressure dependence of the EFG obtained from the present measurements is far weaker than the pres-sure dependence of the calculated lattice contribution. Our results support previous suggestions that va-lence effects are important in determining the EFG in these semimetals. 
  Reference    Z. Naturforsch. 53a, 501—503 (1998); received March 24 1998 
  Published    1998 
  Keywords    EFG, NQR, Arsenic, Antimony, Pressure 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0501.pdf 
 Identifier    ZNA-1998-53a-0501 
 Volume    53 
2Author    Zhengwei Su, Philip CoppensRequires cookie*
 Title    Electrostatic Properties of Molecules from the X-Ray Charge Density. Application to Deuterated Benzene, 1-Alanine and d,l-Histidine  
 Abstract    It has been shown (Z. Su and P. Coppens, Acta Cryst. A 48, 188 (1992)) that the electrostatic potential, the electric field, and the electric field gradient (EFG) can be expressed in closed forms in terms of the positions and the charge-density parameters of individual atoms, whose aspherical density is described by a pseudoatom model (e.g., N. Hansen and P. Coppens, Acta Cryst. A 34, 909 (1978)). A Fortran program Molprop91 based on this method has been written (Z. Su, State Univ. of New York at Buffalo 1991). The method has been applied to the title compounds. Low-temper-ature X-ray diffraction data of fully deuterated benzene (G. A. and d,/-histidine (N. Li, Ph.D. thesis, State University of New York at Buffalo 1989) were analyzed using the least-squares deformation density refinement program Lsmol90 (a modified version of Molly). Molprop91 was subsequently used to calculate the electrostatic-poten-tial maps in selected sections, and at the nuclear positions. For the latter, the EFGs were also evaluated. The electrostatic potentials were used to fit net atomic charges and estimate the molecular energies. Errors in the derived quantities are given. 
  Reference    Z. Naturforsch. 48a, 85—90 (1993); received April 23 1992 
  Published    1993 
  Keywords    Electron density, Electrostatic potential, Electric field, EFG, Molecular energy 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0085.pdf 
 Identifier    ZNA-1993-48a-0085 
 Volume    48 
3Author    P. Wodniecki, A. Kulińska, B. Wodniecka, A. Z. HrynkiewiczRequires cookie*
 Title    Electric Field Gradients at the In Site in Au-In Compounds  
 Abstract    The quadrupole interaction in Au-In compounds of different stoichiometrics was studied with the perturbed angular correlation technique. The electric field gradients at 11 : Cd probes were measured and the temperature dependences of the quadrupole frequencies were determined. A new high temperature phase of Auln above 630 K and a new metastable modification of Au 7 In 3 were found. 
  Reference    Z. Naturforsch. 53a, 349—354 (1998); received October 31 1997 
  Published    1998 
  Keywords    Perturbed Angular Correlations, EFG, Intermetallic Compounds, Au-In System 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0349.pdf 
 Identifier    ZNA-1998-53a-0349 
 Volume    53 
4Author    P. Wodniecki, B. Wodniecka, A. Kulińska, A. Z. HrynkiewiczRequires cookie*
 Title    Electric Quadrupole Interaction at 181 Ta in Isostructural Orthorhombic Cu 8 Hf 3 and Cu 8 Zr 3 Compounds  
 Abstract    The quadrupole interaction of 181 Ta probes in isostructural Cu 8 Hf 3 and Cu 8 Zr 3 intermetallic compounds was studied in the temperature range 24 K -1100 K with the time-differential perturbed angular correlation technique. Two nonaxial electric field gradients corresponding to two nonequiv-alent hafnium or zirconium sites in the investigated structure were found. A linear decrease in the quadrupole interaction frequency with increase of temperature for the 8(d) sites was evidenced, while the v Q (T) dependence for the 4(c) sites is weaker and has a T 312 character. 
  Reference    Z. Naturforsch. 53a, 355—357 (1998); received October 31 1997 
  Published    1998 
  Keywords    Hyperfine Interactions, Perturbed Angular Correlations, EFG, Intermetallic Compounds, Cu-Hf and Cu-Zr Systems 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0355.pdf 
 Identifier    ZNA-1998-53a-0355 
 Volume    53