Highly charged ion
A highly charged ion (HCI, highly charged ion ) is an atom that has lost many electrons and therefore has a high positive electrical charge .
The maximum achievable positive charge is that of the "naked" atomic nucleus , i.e. the number of protons in the atomic nucleus. For example, an iron atom (chemical symbol Fe), the nucleus of which contains 26 protons, can release 13 electrons at temperatures of around 1 million degrees in the solar corona and appear as a 13-fold positively charged ion. In solar flares , ions can even occur because of the much higher temperature .
Ions to which a single electron is still bound are called hydrogen-like , after the element hydrogen , which has only one electron in its neutral state; analogously, helium-like , lithium-like , etc. (after the elements helium , lithium , which have two or three electrons in the neutral state) are those who still have two or three electrons.
The number of bound electrons determines the basic structure of the emission spectrum of these ions, which can therefore be classified in isoelectronic series . Within such an isoelectronic series, the emission lines of the spectrum become shorter and shorter-wave with increasing positive charge of the ion. H. more energetic, but their number and relative arrangement remain largely unchanged.
Due to their emission lines, highly charged ions allow the analysis of the chemical composition, temperature and density of extremely hot plasmas in astrophysics using telescopes and spectrographs , see plasma diagnostics . Similar methods are used to study magnetically confined plasmas in nuclear fusion research .
In the laboratory, it is possible to examine highly charged ions using heavy ion accelerators and the electron beam ion trap .
literature
- HF Beyer, H.-J. Kluge, VP Shevelko, in: X-ray Radiation of Highly Charged Ions , Springer Series on Atoms and Plasmas, Springer Verlag, Berlin-Heidelberg 1997