Spectator electrons

A. The aluminum makes up the anode, and the tin makes up the cathode. The best way to start is to add the spectator electrons to both sides of the equation to balance the positive charges of the cations. This gives you the equation... 

Also called resonance Auger or autoionization spectator transition the spectator electron may also change its orbital, nt -> n t, mostly with t = t (shake-modified spectator transitions) see Section 5.1.2.1. 

The Feynman diagram for the simplest annihilation event shows that annihilation is possible when the two particles are Ax h/mc 10 12 5 m apart, and that the duration of the event is At h/mc2 10-21 s. The distance is the geometric mean of nuclear and atomic dimensions, which is probably not significant. The distance is so much smaller than electronic wave functions that it may be assumed to be zero in computations of annihilation rates. The time is so short that, during it, a valence electron in a typical atom or molecule moves a distance of only ao/104, so that a spectator electron can be assumed to be stationary and the annihilating electron can be assumed to disappear in zero time. Thus the calculation of annihilation rates requires the evaluation of expectation values of the Dirac delta function, and the relaxation of the daughter system (post-annihilation remnant) can be understood with the aid of the sudden approximation [4], These are both relatively simple computations, providing an accurate wave function is available. 

The spectator electrons approximation (SEA) puts the most restrictive interpretation on the nature of a single electron excitation. What we suppose is that only one electron is involved in a transition, and that all the others act as spectators, i.e. that they do not change their properties in any way as a result of the transition. Although it is actually quite rare that this approximation works completely, it provides a good starting point, and can be considered as yet another kind of propensity rule (cf section 4.2), which reduces the number of strong transitions in a spectrum below the number allowed by the usual selection rules. 

FIGURE 11.13 Detail of the spectrum in Figure 11.12 around thels2p Pn Is Sq transitions. The two lines next to the peak are due to Li-like transitions with a spectator electron in n = 3-5 shells (satellite lines). 

The relationship is most sensitive for the small atoms of period 2. Based on dissociation energies, the atoms B to F have the exponent = 6, except for C with H = 5. Judging by interatomic distance, however, B and C appear to be of first order whereas O, N and F have = 5. We interpret this trend in terms of increasing spectator electron density in the relatively small valence shells of these atoms. The dissociation energies seem to indicate a gradual decrease in bond order from C to F of the form 1, < 1, >, . Higher-order bonds of these atoms will be shown to have golden exponents n = 6 b. 

Figure 6 Energy diagram for auto-ionization. An L shell electron is excited to an outer nl shell. Subsequently, an M shell electron fills up the L shell vacancy. In case A, the excited electron in the nl shell leaves the atom, and in case B, another M shell electron leaves the atom while the nl shell electron remains a spectator electron.

Satellite lines These are weaker lines arising from doubly excited ions of higher ionization states. The satellite lines of H-like ions are due to He-like ions, those of He-like ions are due to Li-like ions and so on. For example, transitions in Li-like ions of the type Is nlnT Is nT will appear as a satellite to Is nl-ls resonance transitions in He-like ions (Figure 11). The nT electron is a spectator electron. Due to the presence of this electron. Coulomb shielding decreases, which results in the transition occurring at a slightly lower energy than that of the resonance transition. Since two electrons are involved in such transitions (one active, one spectator), these lines are also referred to as dielectronic satellites. 

The largest separation from a parent line occurs when the spectator electron is in the lowest n level (i.e. n = l) when the Coulomb shielding effect is maximum. These satellites are referred to as 2 s or 2p satellites. For example, the Is 2s 2p - Is 2s transition in Li-like ions will be a 2s satellite for the Is 2p - Is (He-a) transition in He-like ions (Figure 11) Satellites of H-like ions in the Gabriel notation are... 

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