Peculiarities of multiply charged ions

Extensive studies of energy spectra and other characteristics of atoms and ions allow one to reveal general regularities in their structure and properties [255-257]. For example, by considering the lowest electronic configurations of neutral atoms, we can explain not only the structure of the Periodical Table of elements, but also the anomalies. The behaviour of the ionization energy of the outer electrons of an atom illustrates a shell structure of electronic configurations. 

Multiply charged ions represent a peculiar world, essentially differing from the world of neutral atoms or their first ions. In this chapter we shall try to describe these peculiarities. Main attention will be paid to the need for a combination of theoretical and experimental studies of the spectra of highly ionized atoms, and to the role of relativistic and correlation effects for multiply charged ions, and to the regularities and irregularities of the behaviour of their spectral characteristics along isoelectronic sequences. 

Some complex excited configurations possess a large number of levels. This leads to an abundance of close-lying fines, which, due to Doppler broadening cannot always be resolved. Thus, a new type of spectra, called quasicontinuous , appears for multiply charged ions. For the description of such spectra the statistical approach, discussed in the following chapter, seems to be very promising. 

It follows from (31.2) that for large Z this energy separation (wavelength of the appropriate electronic transition) is proportional to Z2. The analogous quantity for configurations with the same n (i.e. An = 0) is 

DHF approach is the most accurate only DHF may be utilized for even more highly ionized atoms, when the relativistic effects are already quite large and, therefore, cannot be accounted for as corrections. 

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