Electron distribution curve

In Fig. 2 the correlation between the electron distribution curve (EDC) of the solid sample and the distribution of kinetic energies is sketched. The binding energies of the electronic levels can be calculated from the kinetic energy by... 

Fig. 2. Projection of electron distribution curve EDC of a sample onto kinetic energy distribution measured by the analyzer.

Photoelectron spectroscopy and measurements of the specific heat and magnetic susceptibility are methods available to gain information about the DOS. In disordered systems, the former gives electron-distribution curves (EDC) reflecting the band density of states [5.61]. Whereas the UPS-method reveals the shape of the DOS and hardly gives the absolute value of the density of states, specific heat as well as susceptibility measurements, on the other hand, give only N(EF). 

With the same sample, we performed micro-photoelectron spectroscopy (p-PES) at selected positions in the channel. With this technique a built-in spectrometer is used to record an electron distribution curve (EDC) with an iris aperture limiting the area of the detected photoelectrons to a range of about 30 pm. The spectra represent the integrated energy distribution of the photo-eleetrons. 

Fig. 4.26. Electron distribution curve in a-Ge at various photon energies in a-Ge (after Spicer and Donovan (1970b)).

Figure 5. Radial electron distribution. Curve a distribution characterizing Ir Y zeolite (no Ir-Ir distances can be observed). Curve b distribution obtained after treatment of the sample with a CO+H2 mixture (the large peak at 2.78 A corresponds to Ir6(C0)i5 clusters).

Figure 5.2 The modification of the electron energy distribution curve by the presence of diffraction limits in a crystal. The lower filled band is separated from upper unoccupied states in a semiconductor by a small energy difference, so that some electrons can be promoted to conduction by an increase in temperature...

This description provides information, via conventional structures, about the constitution of reactants, products, and the intermediate. Transition state structures are more provisional and may attempt to show the electronic distribution and flow in this region of the reaction path. The curved arrow symbolism is often used, as shown in structure 1 for the first elementary reaction. 

Because of the difficulty of obtaining satisfactory photometer records of electron diffraction photographs of gas molecules, we have adapted and extended the visual method to the calculation of radial distribution curves, by making use of the values of (4t sin d/2)/X obtained by the measurement of ring diameters (as in the usual visual method) in conjunction with visually estimated intensities of the rings, as described below. Various tests of the method indicate that the important interatomic distances can be determined in this way to within 1 or 2% (probable error). 

Model A cannot be eliminated definitely by the photographs there are, however, some points which make this model improbable. From the curve for this model the first minimum would be expected to be at least as well pronounced as the second minimum, whereas on the photographs the first minimum is not very well defined. That the qualitative appearance of the photographs supports model C rather than model A is further shown by the fact that the photographs resemble those of methyl nitrate more closely than those of carbon tetrafluoride. Some evidence is also provided by the radial distribution curve (Fig. 1), the first peak being displaced by 0.15 A. from the position expected for it for model A. For these reasons and the additional reason that it is difficult to correlate the tetrahedral configuration with an electronic structure involving only completed octets, we consider model A not to be satisfactory.7... 

Fig. 5.2 Radial distribution curves, Pv

Figure 3. ARUPS energy distribution curves taken with Hel radiation at normal incidence and an electron emission angle of 52" shown as a function of copper coverage. The intensity of the various curves has been normalized at the Fermi level Ef The individual curves are matched to their corresponding copper coverages in monolayers by the solid lines and the saturation behavior of the interface state at approximately —1.5 eV is identified by the dashed lines. (Data from ref. 8.) (Reprinted with permission from ref. 43. Copyright 1987 American Association for the Advancement of Science.)...

Fig. 2- State density distribution curve of electrons in solid ZXe) = electron state density tu = uiq>er band edge = lower band edge.

Fig. 2-8. State density distribution curve of 3d and 4s frontier bands partially occupied by electrons in metallic iron [From Fiyita, 1996.]...

Fig. 2-13. Schematic electron state density distribution curves in the valence and conduction bands of silicon cc = conduction band edge level Cv = valence band edge level c, = band gap (1.1 eV for silicon) CB = conduction band V6 = valence band.

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