Kinetic energy distribution

Figure Al.7.12 shows the scattered electron kinetic energy distribution produced when a monoenergetic electron beam is incident on an A1 surface. Some of the electrons are elastically backscattered with essentially...

Figure Al.7.12. Secondary electron kinetic energy distribution, obtained by measuring the scadered electrons produced by bombardment of Al(lOO) with a 170 eV electron beam. The spectrum shows the elastic peak, loss features due to the excitation of plasmons, a signal due to the emission of Al LMM Auger electrons and the inelastic tail. The exact position of the cutoff at 0 eV depends on die surface work fimction.

Photoelectron spectroscopy provides a direct measure of the filled density of states of a solid. The kinetic energy distribution of the electrons that are emitted via the photoelectric effect when a sample is exposed to a monocluomatic ultraviolet (UV) or x-ray beam yields a photoelectron spectrum. Photoelectron spectroscopy not only provides the atomic composition, but also infonnation conceming the chemical enviromnent of the atoms in the near-surface region. Thus, it is probably the most popular and usefiil surface analysis teclmique. There are a number of fonus of photoelectron spectroscopy in conuuon use. 

Fig. 8-4. Effect of temperature on atomic (or molecular) kinetic energy distribution.

The problems of distinguishing H+ produced from H2 by electron impact from the product of dissociative charge transfer reactions between He + and H2 can be studied by determining the kinetic energy distribution in the product H+ (6). The reaction He+ + H2 is exothermic by 6.5 e.v. if the products are atoms or atomic ions. If the reaction is studied with HD substituted for H2, then the maximum kinetic energy that can be deposited in the D + is approximately 2.16 e.v. On the other hand, D + can be produced by electron impact with 5.5 e.v. kinetic energy. If a retarding potential is applied at the repeller in the ion-source of a mass spectrometer, then it is possible to obtain curves related to the kinetic... 

The technique of measuring the 0+ kinetic energy distribution produced by reaction of He + and 02 showed promise for establishing the existence of HeO+. Experiments with He3 and He4 isotopes and 02 were carried out in the ion source of a mass spectrometer. Retarding potential curves for O + in the two systems were determined, and the com-... 

Normalized ion intensities are plotted as a function of retarding voltage. The unlabeled curve gives the observed kinetic energy distribution for reactant zHe and AHe ions shaded and open squares). 

At a given temperature, all gases have the same molecular kinetic energy distribution. 

Photoemission has been proved to be a tool for measurement of the electronic structure of metal nanoparticles. The information is gained for DOS in the valence-band region, ionization threshold, core-level positions, and adsorbate structure. In a very simplified picture photoemission transforms the energy distribution of the bounded electrons into the kinetic energy distribution of free electrons leaving the sample, which can easily be measured ... 

The internal energy of the O2 fragment is found from the total kinetic energy distribution using the energy conservation equation... 

Fig. 3. Total kinetic energy distribution for O3 — C Ag) + 0(1D2). Also shown at each wavelength is a comb corresponding to each vibrational level with no rotational excitation. The peaks observed in the 305 nm image are due to rotational structure. The small peak at 0.19eV in the 305nm image is due to an ozone hot band .

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

Figure 6.8 (a) Translational kinetic energy distribution for an ideal gas (equation 6.3-7) (b) velocity distribution for N2 molecules (equation 6.3-8)... 

Fig. 6. Experimental and calculated angle-integrated kinetic energy distributions. In all cases the curves are peak normalized. Modeled from Ref. 9.)...

Fig. 4.5. Effects of initial time, space, and kinetic energy distributions on mass resolution in TOF-MS. Adapted from Ref. [34] with permission. American Chemical Society, 1992.

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