Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Electron structure factor

Much of the available experimental information on intermetallic compounds comes from high-energy electron diffraction (HEED) measurements. In electron diffraction, the electron beams interact with the electrostatic potential in the crystal. The electron structure factor is therefore directly dependent on this... [Pg.265]

The position of the intensity minimum depends sensitively on the ratio of the first- and second-order electron structure factors. It is commonly assumed that the second-order structure factor can be described in the independent-atom... [Pg.266]

As has been previously mentioned, the two most important electronic structure factors that have been suggested to stabilize the TP geometry in... [Pg.179]

Figure 9 An example of the best fit obtained from an electron structure factor refinement. The experimental intensities are from a few selected line scans across the experimental pattern shown in (a). The fit was obtained using Si(lll) and (222) strucmre factors as adjustable parameters together with parameters describing the electron diffraction geometry... Figure 9 An example of the best fit obtained from an electron structure factor refinement. The experimental intensities are from a few selected line scans across the experimental pattern shown in (a). The fit was obtained using Si(lll) and (222) strucmre factors as adjustable parameters together with parameters describing the electron diffraction geometry...
The structural parameters are the atomic positions, Debye-Waller factors, electron structure factors, and electron diffraction parameters, which include the absorption potential, sample thickness, and crystal orientation. Not all parameters can be refined together. Diffraction patterns that are sensitive to certain parameters are collected and they are often refined independently. Figure 9 shows an example of a structure factor measurement by fitting CBED intensities recorded in the systematic orientation where one row of reflections are set at or near the Bragg conditions. Details about this method and its applications for structure factor measurement and atomic structure refinement are given in Ref. 18 and 43. [Pg.6030]

Fig. 12. Near-infrared MCD spectrum recorded at 4.2 K for six low-spin heme proteins, each containing protoheme IX with histidine as one ligand but with different second ligands. The spectra illustrate the sensitivity of the near-IR MCD to the ligation of the heme ring and demonstrate that MCD in this region can be used to assign axial ligands. The near-IR MCD spectra, in combination with EPR, were also used to determine the electronic structure factors for the proteins. (From Gadsby and Thomson, with permission.)... Fig. 12. Near-infrared MCD spectrum recorded at 4.2 K for six low-spin heme proteins, each containing protoheme IX with histidine as one ligand but with different second ligands. The spectra illustrate the sensitivity of the near-IR MCD to the ligation of the heme ring and demonstrate that MCD in this region can be used to assign axial ligands. The near-IR MCD spectra, in combination with EPR, were also used to determine the electronic structure factors for the proteins. (From Gadsby and Thomson, with permission.)...
However, donor-acceptor interactions are affected not only by the Lewis acid and base strengths, but also by other, steric and electron structural, factors. Thus, even in systems where either solely the donor or the acceptor property of the solvent is manifested, solvents with different space requirements may interact to different extents because of the steric properties of the reference solute and a reference acceptor with a tendency for dative 7c-bonding (back-coordination) will interact more strongly with jr-acceptor solvent molecules (e.g., acetonitrile) than would be expected from their basicity. The solvent donicity investigations by Burger et al [Bu 71, 74] with transition metal complex reference acceptor model systems have clearly shown the great extent to which such secondary effects may distort the solvent scale. [Pg.43]

Tsirelson et measured very accurate electron structure factors and used them in a high-resolution quantitative study of the electrostatic potentials in LiF, NaF, and MgO crystals. A topological analysis of the electrostatie potential, defining the features of the electrostatic field and the Coulomb foree field in a crystal, was developed. In addition to an AIM analysis this approach provides a more complete description of the atomic interactions according to the authors. [Pg.419]

It is clear from the discussion of potential energy diagrams in Chapter 2, scaling relations in Chapter 6, electronic structure factors in Chapter 8 that adsorption energies and activation barriers for elementary surface reactions can depend stfongly on the local structure of the surface where they take place. In this section, we provide a discussion of the possible consequences of this on the rate for a complete reaction. [Pg.139]


See other pages where Electron structure factor is mentioned: [Pg.143]    [Pg.265]    [Pg.266]    [Pg.266]    [Pg.266]    [Pg.21]    [Pg.173]    [Pg.178]    [Pg.173]    [Pg.178]    [Pg.6022]    [Pg.240]    [Pg.239]    [Pg.246]    [Pg.271]    [Pg.193]    [Pg.2]    [Pg.6021]    [Pg.158]    [Pg.24]    [Pg.708]    [Pg.309]    [Pg.360]    [Pg.361]    [Pg.859]   
See also in sourсe #XX -- [ Pg.266 ]




SEARCH



Electron density from structure factors

Electron electronic factor

Electronic factors

Electronic structures stability factors

Hyperfine structure and bound-electron g-factor

Structural factors

Structure factor

© 2024 chempedia.info