scholarly journals Least-Squares Determination of Molecular Structures from Gaseous Electron-Diffraction Data. II. Polynomial Expression of Background

1972 ◽  
Vol 45 (6) ◽  
pp. 1631-1634 ◽  
Author(s):  
Shuzo Shibata
Keyword(s):  
Electron Diffraction ◽  
Least Squares ◽  
Diffraction Data ◽  
Molecular Structures ◽  
Electron Diffraction Data ◽  
Gaseous Electron ◽  
Polynomial Expression

scholarly journals Procedure and Computer Programs for the Structure Determination of Gaseous Molecules from Electron Diffraction Data.

1969 ◽  
Vol 23 ◽  
pp. 3224-3234 ◽  
Author(s):  
B. Andersen ◽  
H. M. Seip ◽  
T. G. Strand ◽  
R. Stølevik ◽  
Gunner Borch ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Computer Programs ◽  
Electron Diffraction Data

STRUCTURE DETERMINATION OF THE Ge(111)-(3×1)Ag SURFACE RECONSTRUCTION

1999 ◽  
Vol 06 (06) ◽  
pp. 1061-1065 ◽  
Author(s):  
D. GROZEA ◽  
E. BENGU ◽  
C. COLLAZO-DAVILA ◽  
L. D. MARKS
Keyword(s):  
Electron Diffraction ◽  
Surface Reconstruction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Heavy Atom ◽  
Direct Methods ◽  
Electron Diffraction Data ◽  
Transmission Electron ◽  
First Time

For the first time, during the investigation of the Ag submonolayer on the Ge(111) system, large, independent domains of the Ge (111)-(3×1) Ag phase were imaged and investigated. Previous studies have reported it only as small insets between Ge (111)-(4×4) Ag and Ge (111)- c (2×8) domains. The transmission electron diffraction data were analyzed using a Direct Methods approach and "heavy-atom holography," with the result of an atomic model of the structure similar to that of Ge (111)-(3×1) Ag .

The use of Direct Phasing Methods for Single Crystal Electron Diffraction Data. I. Methylene Subcells

1976 ◽  
Vol 34 ◽  
pp. 544-545
Author(s):  
D. L. Dorset ◽  
H. A. Hauptman
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Crystal Structure Analysis ◽  
Electron Diffraction Data ◽  
Trial And Error ◽  
Mosaic Crystals ◽  
Crystal Electron ◽  
Kinematical Theory

The significant impediment to the use of electron diffraction data for crystal structure analysis is, of course, the perturbation of n-beam dynamical effects. In more severe cases this dynamical perturbation gives an intensity distribution in the diffraction pattern which is not directly related to the underlying crystal structure, thus making the determination of complex structures nearly impossible by this technique.However, as was experimentally established in Vainshtein's laboratory and is theoretically predicted, the diffraction of electrons from thin mosaic crystals composed of light atoms is in accord with kinematical theory to a good first approximation and, furthermore, ab initiocrystal structure analyses are tractable viastandard crystallographic phase determination. To date the few electronographic determinations of unknown organic structures have used either trial and error or Patterson techniques.

Molecular structures of dichloro(dimethyl)germane and trichloro(methyl)germane determined by vapour phase electron diffraction

1977 ◽  
Vol 55 (6) ◽  
pp. 1104-1110 ◽  
Author(s):  
John E. Drake ◽  
J. Lawrence Hencher ◽  
Quang Shen
Keyword(s):  
Electron Diffraction ◽  
Diffraction Data ◽  
Confidence Level ◽  
Systematic Errors ◽  
Vapour Phase ◽  
Molecular Structures ◽  
Electron Diffraction Data ◽  
Geometrical Parameters ◽  
Methyl Group ◽  
Uncertainty Estimates

The molecular structures of dichloro(dimethyl)germane and trichloro(methyl)germane have been determined in the vapour phase by electron diffraction. The principal geometrical parameters for (CH3)2GeCl2 are rg(Ge—Cl) = 2.143 ± 0.004 Å, rg(Ge—C) = 1.928 ± 0.006 Å, [Formula: see text].and [Formula: see text] In the analysis of CH3GeGl3 recently reported values of the rotational constants were combined with the electron diffraction data to give rg(Ge—Cl) = 2.132 ± 0.003 Å, rg(Ge—C) = 1.893 ± 0.010 Å, [Formula: see text] and [Formula: see text]In both cases the methylgermane geometry was assumed for the methyl group [Formula: see text] which was fixed in the staggered configuration with respect to the C2GeCl2 and CGeCl3 frames respectively. Both random and systematic errors were included in the uncertainty estimates, which are believed to be approximately at the 95% confidence level. In the case of (CH3)2GeCl2 the uncertainties in [Formula: see text] were enlarged to four times the least-squares values in order to reflect the difficulty of resolving the Cl … Cl, C … Cl, and C … C distances in the analysis.

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