X-ray spectra and the spinning electron.

The theory of the spinning electron has led to a new insight into the meaning of the multiple structure of X-ray spectra and has cleared up the theoretical difficulties which were met with in the attempts to account for the so-called screening and relativity doublets of these spectra by relativity considerations alone; it promises also to throw light on the so-called‘ branching’ of spectra, which usually accompanies the addition of a further electron to an atom and of which so far no satisfactory explanation has been given.

X-ray spectra (Kossel's theory).

The electrons revolving round the nucleus form the K, L, M,…. shells reckoning outwards from the nucleus, the corresponding principal quantum numbers being n = 1, 2, 3,…

A K line of the X-ray spectrum is produced by the ejection of a K electron from the atom and its replacement by an electron from one of the outer shells L, M, …, which transition causes the radiation; an L line is due to the ejection of an L electron and its replacement by an electron from one of the outer shells M, N, …; and so on. The K lines tend to a limit corresponding to the fall of an electron from the edge of the atom to a K level. This limit is found by observation of the ‘absorption edge’ of the K lines, and if v is the frequency corresponding to this ‘edge,’ hv is the energy ‘term’ of the K group.