The asymmetry parameter of the electric field gradient in molecular crystals

1967 ◽  
Vol 7 (1) ◽  
pp. 103-106
Author(s):  
N. E. Ainbinder ◽  
V. S. Grechishkin ◽  
A. N. Osipenko
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Asymmetry Parameter ◽  
Molecular Crystals ◽  
The Asymmetry

Orientation of the EFG Tensor with Respect to the Heme Group of Deoxymyoglobin

1976 ◽  
Vol 31 (4) ◽  
pp. 487-490 ◽  
Author(s):  
Y. Maeda ◽  
T. Harami ◽  
A. Trautwein ◽  
U. Gonser
Keyword(s):  
Electric Field ◽  
Single Crystal ◽  
Electric Field Gradient ◽  
Coordinate System ◽  
Field Gradient ◽  
Asymmetry Parameter ◽  
Principal Axis ◽  
Heme Group ◽  
Principal Axis System ◽  
The Asymmetry

Following Zimmermann’s method of correlating intensity tensors from single crystal Mössbauer spectra with electric field gradient (EFG) tensors we are able to derive a manyfold of solutions for the orientation of the principal axis system of the local EFG with respect to the heme coordinate system in deoxymyoglobin. Comparing these results with theoretical estimates of the asymmetry parameter η we are able to limit the range of possible orientations of , and we find Vẑẑ to be rather close to the heme plane with a deviation from that of at most 14°.

STUDY OF THE RELATIONSHIP BETWEEN STRUCTURE AND O-17 ELECTRIC FIELD GRADIENT PARAMETERS IN SOME ALUMINOSILICATES

2005 ◽  
Vol 19 (24) ◽  
pp. 1213-1221 ◽  
Author(s):  
ERDEM KAMIL YILDIRIM ◽  
RAY DUPREE
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Local Structure ◽  
Asymmetry Parameter ◽  
Bond Angle ◽  
Theoretical Work ◽  
The Relationship ◽  
Oxygen Site

The relation between O-17 quadrupolar parameters and the local structure in silicates is of considerable interest if these parameters are to be used as a local probe. Although there are a number of investigations and some theoretical work on Si—O—Si bonds, there seems to be very little experimental data on Si—O—Al bonds. We have therefore investigated a number of sodalites with a general formula of M 8 [AlSiO 4 ]Cl 2 where M is an alkali cation. They have only one oxygen site and a Si:Al ratio of one. By varying the alkali we were able to change the Si—O—Al bond angle about five degrees steps from 125 to 152 degrees. The value of the electric field gradient (EFG), CQ of O-17, followed a roughly similar angular dependence to that found for Si—O—Si bonds with CQ180= 4.2 MHz . The asymmetry parameter of O-17 also behaved in a similar fashion to that found for Si—O—Si bonds although it increased more rapidly at small angles.

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