Energy distribution of secondary

It is important to know the energy distribution of secondary ions because it has consequences for their detection, especially in the case of insulators. As Fig. 4.5 shows, the energy distribution of elemental secondary ions usually has a peak between 15 and 30 eV, falls off rapidly at higher energy but exhibits a low-level tail to a few... 

Figure 4.5 Energy distribution of secondary Cu+, Cu2+ and Cu3+ ions during bombardment of copper with 10 keV Ar+ ions curves have been normalised to the same height (data from Dennis and MacDonald [10]).

Single-differential cross sections are difficult to obtain in a direct measurement and they are usually obtained by numerical integration of the double-differential cross sections over all angles (2.28). The singledifferential cross section describes the energy distribution of secondary electrons and is therefore important in modelling radiation damage, in studies of stellar and upper atmospheric phenomena, plasma fusion work. 

Delcorte, A., Bertrand, P. (1996) Kinetic energy distributions of secondary molecular ions from thin organic films under ion bombardment. Nucl. Instrum. Meth. Phys. Res. B, 115,246-250. 

Recorded kinetic energy distributions of secondary ions (secondary ion intensity versus emission energy) display a peak at around 2-5 eV emission energy whereupon they drop in intensity. Molecular ion intensities decrease more rapidly than those for atomic secondary ions. Indeed, the latter can extend out to several hundred eV. Decreased matrix effects are also noted for the higher emission energy secondary ions. 

Auger electron spectroscopy (AES) is a technique used to identify the elemental composition, and in many cases, the chemical bonding of the atoms in the surface region of solid samples. It can be combined with ion-beam sputtering to remove material from the surface and to continue to monitor the composition and chemistry of the remaining surface as this surface moves into the sample. It uses an electron beam as a probe of the sample surface and its output is the energy distribution of the secondary electrons released by the probe beam from the sample, although only the Ai er electron component of the secondaries is used in the analysis. 

Fig. 27. Product translational energy distribution of the H-atom production channel in the secondary photodissociation of ethoxy radical at 193.3 nm. The onsets of the relevant electronic states of the possible CH3CHO product are indicated in the figure. The signals from the primary photodissociation of ethanol are labelled. (FYom Xu et al.171)...

Angular distribution of secondary electrons for the ejected energy w > 200 eV was calculated using the kinematical relationships... 

Fig. 2.5 An ion kinetic energy distribution of field desorbed He ions taken with a pulsed-laser time-of-flight atom-probe. In pulsed-laser stimulated field desorption of field adsorbed atoms, atoms are thermally desorbed from the surface by pulsed-laser heating. When they pass through the field ionization zone, they are field ionized. Therefore the ion energy distribution is in every respect the same as those in ordinary field ionization. Beside the sharp onset, there are also secondary peaks due to a resonance tunneling effect as discussed in the text. The onset flight time is indicated by to, and resonance peak positions are indicated by arrows. Resonance peaks are pronounced only if ions are collected from a flat area of the...

Fig. 2.6 (a) Field ion energy distributions of H+, Hj and H3 ions obtained by Jason et al.21 Secondary peaks due to resonance field ionization are most pronounced for f/J. are formed right near the surface, and no low energy tail... 

The interaction of keV particles with solids has been characterized by the measurement of the angle and energy distribution of sputtered secondary ions and neutrals. The results are compared to classical dynamics calculations of the ion impact event. Examples using secondary ions are given for clean Ni 001), Cu 001) reacted with 0>, Ni 001 and Ni 7 9 11 reacted with CO, and Agllll) reacted with benzene. The neutral Rh atoms desorbed from Rh 001 are characterized by multiphoton resonance ionizaton of these atoms after they have left the surface. 

Angular distribution of neutral atoms angular distributions, 94,95f energy distributions, 93-9 1 schematic of detector, 93,94f Angular distribution of secondary Ions adsorbate-covered... 

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