Energy distribution secondary ions

Secondary ion energy distribution About 3 eV average, depending on sample no high energy tail as with atomic species... 

Secondary ion energy distributions for both atomic and molecular species peak at around a few electron volts. This is generally higher for atomic versus molecular secondary ions. 

Figure 5.10 Example of the effect of positive charge buildup on the positive secondary ion energy distribution after accounting for the applied accelerating voltage. This was collected from a Silicon surface with the energy window set at 5 eV on a Magnetic Sector SIMS instrument.

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... 

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. 

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]).

The angular dependence of the secondary ion intensity is expected to follow a simple cosine law, in particular for randomly oriented polycrystalline surfaces. The explanation for this is that upon impact the collision cascade takes care of an isotropic distribution of the energy through the sample. Hence the intensity of collision... 

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