Auger States

Another application is to the study of the Auger states in which a further electron ionization of attachment may occur, leaving the system with holes in more than one shell. Such states were considered in some detail by Firsht and McWeeny [9] for free atoms here we have made a preliminary applieation to the nitrogen moleeule. The initial aim is simply to identify and assign the principal peaks and satellites in the Auger spectrum of gaseous N2. 

Auger transitions are due to the transfer of a solid electron to the ion, coupled with the excitation of a second electron into an Auger state of energy in the solid. Thus, the TDAN Hamiltonian is augmented by the terms ... 

Such doubly excited states are familiar in nuclear physics as compound state, or Feshbach, resonances, and In atomic spectroscopy as autolonizlng, or Auger, states of atoms and molecules (33). Just as In the atomic case (33.34), sequences of states with quantum numbers of the form (n,n-t-m) do not necessarily have shorter lifetimes as a function of Increasing m, in contradistinction to statistical expectations. This follows from the Increase In period of the local bond modes as dissociation Is neared, and the detuning of any near frequency resonances as m increases in a sequence of (n,n+m) states. 

The energy and decay widths of the Ne ls2s 2p Auger state... 

The computation of the five partial widths in the nine-electron Ne ls2s 2p Auger state (about 870.3 eV above the Ne ground state) [118,119]. 

As examples, this section discusses briefly four subjecfs where, in conjunction with suitable theoretical support, consideration of just the hoS has provided quantitative as well as semiquantitative general understanding of the nonrelativistic MEP in a variety of autoionizing (Auger) states across the Periodic Table and of the interplay between their electronic structures on the one hand, and energy, photoionization or autoionization spectra on the other. 

A much harder calculation of coherenf fime-dependent excitation and decay in a polyelectronic, open-shell system was published in 2007 [118]. Specifically, as a prototypical application of the SSEA to a complex system, we chose the problem of the time-resolved coherent excitation and decay of the 2s-hole ls 2s2p 3s 3p P° Auger states of Aluminum, where the dominant channels representing one- as well as two-electron continua are taken into account. In the following paragraphs, we explain how these computations were done. 

As another exemplar of the results of these computations [118], we chose to reproduce figure 3 of Ref. [118]. This is shown here as Figure 6.6. It represents the first ab initio theoretical-computational demonstration of the time-resolved formation of the interference-induced asymmetric profile during the creation of an inner-hole Auger state [118,151,153]. 

For the time-dependent picture, Equation 7.36 serves quite well. The probability for a certain continuum state, Cm(t), increases with time. This means that the probability of a state of type (Is oos) also increases with time. The latter state is a so-called Auger state. Thus, the (2s) state decays by moving one electron to Is and ejecting the other. The total energy of the states before and after is the same. 

Electron correlation in the final Auger state can be investigated through transition (2a) or, more directly, through transitions like... 

Because electron correlation is largest in the outermost shell we expect large satellite intensities if the final Auger state involves electrons from this shell. If, in addition, the energies of the final Auger diagram state and of an Cl excited state are close, then we expect very intense FISCI satellites. 

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