Electronic Spectra from Scattered Electrons

An example of the features of the spectrum of secondary electrons emitted in H° impact on water molecules from the work of Bolorizadeh and Rudd [67] is shown in Fig. 16. Compared to the simple spectrum of electrons emitted by proton impact shown as the solid line in Fig. 16 the spectrum from H° impact has an additional peak centered at an electron energy of approximately 82 eV. This broad peak is from the superposition of the spectrum of electrons stripped (elastically scattered) from the projectile on the spectrum of electrons ejected from the target. Because the stripped projectile electrons originate as bound electrons in the rest frame of the moving projectile, their laboratory energy is given approximately hy W = meE jM and the width of the peak is determined by the Compton profile of electrons in the projectile frame, but also transformed to the laboratory frame-of-reference. The results shown in Fig. 16 clearly illustrate that the cross-sections for... 

Consider a time-resolved, electronically nonresonant CARS spectrum from a molecular liquid. In the CARS process, the laser pump pulses create a linear combination (that is the inteimolecular rovibrational coherence) of Raman active rovibrational transitions between molecules at position rr and r in the mixture. This stimulated Raman scattering process is carried out by two-coincident laser pulsesfl, II) with central frequenciesfwave vectors) C0i(k ) and (Oiiikii). By applying the third pulse with C0 (kni) to the liquid after time delay t, the time dependence of the inteimolecular rovibrational coherence is detected through the measurement of the intensity of the scattered photon with kj... 

As the X-ray energy is increased beyond that required for promotion of the core electron, ejection of core electrons into the continuum occurs. This ejected electron propagates from the Mn center until it encounters another atom from which it can be back-scattered. The interference of back-scattered waves with propagating waves leads to an interference pattern that is manifested as an oscillation in the X-ray absorption pattern. Fourier transformation of this oscillating spectrum from the frequency domain to the distance domain gives a new spectrum whose abscissa contains information on the distance between the target atom (i.e., the Mn center) and the back-scattering atoms. This second technique is called Extended X-ray Absorption Fine Structure, EXAFS, and has been the only spectroscopic tech-... 

Electronic transitions within the valence shell of atoms and molecules appear in the energy-loss spectrum from a few electron volts up to, and somewhat beyond, the first ionization energy. Valence-shell electron spectroscopy employs incident electron energies from the threshold required for excitation up to many kiloelectron volts. The energy resolution is usually sufficient to observe vibrational structure within the Franck-Condon envelope of an electronic transition. The sample in valence-shell electron energy-loss spectroscopy is most often in the gas phase at a sufficiently low pressure to avoid multiple scattering of the... 

The oscillating part of the secondary electron spectrum fine structure in the expression obtained is determined by two interference terms resulting from scattering of secondary electrorrs of final and intermediate states (the latter are due to the second-order process only). Here intensities of oscillating terms are determined by the amplitudes and intensities of electron transitions in the atom ionized. In this section we make estimations of these values within the framework of the simple hydrogen like model using the atomic unit system as in the preceding section. This section s content is based on papers [20,22,29-31,33,35,37,45-47]. 

Electron-Dispersive Scattering (EDS) spectra obtained from several regions across the wear track indicated the presence of iron oxides, aluminum (metal and oxide) and zinc (metal and oxide). A typical EDS spectrum from the AIBC QEN4 wear surface is shown in Figure 14. Note that there is no obvious contrast in the image that defines the region containing oxidized iron and aluminum. 

Fig. VIII-10. (a) Intensity versus energy of scattered electron (inset shows LEED pattern) for a Rh(lll) surface covered with a monolayer of ethylidyne (CCH3), the structure of chemisorbed ethylene, (b) Auger electron spectrum, (c) High-resolution electron energy loss spectrum. [Reprinted with permission from G. A. Somoijai and B. E. Bent, Prog. Colloid Polym. ScL, 70, 38 (1985) (Ref. 6). Copyright 1985, Pergamon Press.]...

Figure Bl.6.8 Energy-loss spectra of 200 eV electrons scattered from chlorine at scattering angles of 3° and 9° [10]. Optically forbidden transitions are responsible for the intensity in the 9° spectrum that does not appear in the 3 ° spectrum.

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