Electron recoil

In this section we consider the final-state longitudinal momentum distributions of the ejected electron, recoil-ion, and projectile momentum transfer in the single... 

Normally these conditions are satisfied in fast highly charged ion-atom collisions. From Eq. (66) we can derive the equations for the singly differential cross sections with respect to the components of the longitudinal momentum distributions for the electron, recoil-ion, and projectile. The longitudinal electron momentum distribution da/dpe for a particular value of p, may be derived by integrating over the doubly differential cross section with respect to the electron energy Ek ... 

If an incident photon (pu Ei = pic) hits an electron considered as nearly at rest (0, moc ), producing an electron recoil (po, Eo), the direction of the scattered photon (pi, E2 = pic) makes an angle 0 with that of the incident photon. Applying the laws of conservation of energy and momentum to the scattering process ... 

The Compton Effect. The Compton effect refers to the scattering of incident photons by the interaction with free electrons. Here, an incident photon of energy hvg is scattered into the angle 6, with reduced energy hi/, and the electron recoils through the angle , with increased kinetic energy E (Fig. 26.4). The fact that the electrons are free and not bound to an atom reduces the complexity... 

Ion Beam Analysis Electron Recoil and Rutherford Backscattering... 

While velocity mapped imaging gives a direct picture of momentum space, there are some serious issues using this technique with cold molecules. The two most important are the electron recoil during the ionization step and charge repulsion from producing multiple ions per laser shot. While... 

Fig. 8.9. Left side of the figure shows the differential cross-section for NH3 j = 1 from NH3 j = 0 doped in Kr scattering off of Ne doped in He. The right side is a cross-section of the stationary molecules. The molecules fit to a 15m/s velocity spread (200 mK) which is dictated by our imaging resolution and electron recoil during detection...

The direction of the electron recoil motion can be found by applying the momentum conservation law (see Figure 6.43) p = p + moU From a triangle OCD we can find... 

There are two basic physical phenomena which govern atomic collisions in the keV range. First, repulsive interatomic interactions, described by the laws of classical mechanics, control the scattering and recoiling trajectories. Second, electronic transition probabilities, described by the laws of quantum mechanics, control the ion-surface charge exchange process. 

In TOF-SARS [9], a low-keV, monoenergetic, mass-selected, pulsed noble gas ion beam is focused onto a sample surface. The velocity distributions of scattered and recoiled particles are measured by standard TOF methods. A chaimel electron multiplier is used to detect fast (>800 eV) neutrals and ions. This type of detector has a small acceptance solid angle. A fixed angle is used between the pulsed ion beam and detector directions with respect to the sample as shown in figure Bl.23.4. The sample has to be rotated to measure ion scattering... 

Scattering and recoiling contribute to our knowledge of surface science tln-ough (i) elemental analysis, (ii) structural analysis and (iii) analysis of electron exchange probabilities. We will consider the merits of each of these tluee areas. 

Fig. 6. Schematic illustration of the relationships of the original y-ray and the scattered radiations for Compton scattering where E is the energy of the incident photon, E is the energy of the recoiling electron, and E is the energy of the scattered photon.

Elastic Recoil Detection Analysis Glow discharge mass spectrometry Glow discharge optical emission spectroscopy Ion (excited) Auger electron spectroscopy Ion beam spectrochemical analysis... 

The interface properties can usually be independently measured by a number of spectroscopic and surface analysis techniques such as secondary ion mass spectroscopy (SIMS), X-ray photoelectron spectroscopy (XPS), specular neutron reflection (SNR), forward recoil spectroscopy (FRES), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), infrared (IR) and several other methods. Theoretical and computer simulation methods can also be used to evaluate H t). Thus, we assume for each interface that we have the ability to measure H t) at different times and that the function is well defined in terms of microscopic properties. 

For 7-ray energies below 1 MeV (the range of interest) there are two principal modes of interaction with matter — Compton scattering and photoelectron absorption. Compton scattering is the elastic scattering of the 7 photon by an orbital electron in which part of the incident 7-energy is imparted to the recoiling electron. 

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