Siegbahn notation

The Siegbahn notation is used in X-ray spectroscopy to name the spectral lines that are characteristic to elements. It was introduced by Manne Siegbahn.

The characteristic lines in X-ray emission spectra correspond to atomic electronic transitions where an electron jumps down to a vacancy in one of the inner shells of an atom. Such a hole in an inner shell may have been produced by bombardment with electrons in an X-ray tube, by other particles as in PIXE, by other X-rays in X-ray fluorescence or by radioactive decay of the atom's nucleus.

Although still widely used in spectroscopy, this notation is unsystematic and often confusing. For these reasons, International Union of Pure and Applied Chemistry (IUPAC) recommends another nomenclature.

History

The use of the letters K and L to denote X-rays originates in a 1911 paper by Charles Glover Barkla, titled The Spectra of the Fluorescent Röntgen Radiations^[1] ("Röntgen radiation" is an archaic name for "X-rays"). By 1913, Henry Moseley had clearly differentiated two types of X-ray lines for each element, naming them α and β.^[2] In 1914, as part of his thesis, Ivar Malmer (sv:Ivar Malmer), a student of Manne Siegbahn, discovered that the α and β lines were not single lines, but doublets. In 1916, Siegbahn published this result in the journal Nature, using what would come to be known as the Siegbahn notation.^[3]

Correspondence between the Siegbahn and IUPAC notations

The table below shows a few transitions and their initial and final levels.

Initial level	Final level	Siegbahn notation	IUPAC notation
K (1s1/2^−1)	L3 (2p3/2^−1)	Kα1	K–L3
	L2 (2p1/2^−1)	Kα2	K–L2
	M3 (3p3/2^−1)	Kβ1	K–M3
	M2 (3p1/2^−1)	Kβ3	K–M2
L3 (2p3/2^−1)	M5 (3d5/2^−1)	Lα1	L3–M5
	M4 (3d3/2^−1)	Lα2	L3–M4
L2 (2p1/2^−1)	M4 (3d3/2^−1)	Lβ1	L2–M4
M5 (3d5/2^−1)	N7 (4f7/2^−1)	Mα1	M5–N7

See also

• Characteristic X-ray
• Moseley's law
• X-ray notation

References

1. Barkla, Charles G (1911). "The Spectra of the Fluorescent Röntgen Radiations". The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science. 22 (129): 396–412. doi:10.1080/14786440908637137.
2. Henry Moseley (1913). "The high-frequency spectra of the elements". The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science. 26 (156): 1024–1034. doi:10.1080/14786441308635052.
3. MANNE SIEGBAHN (17 Feb 1916). "Relations between the K and L Series of the High-Frequency Spectra". Nature. 96 (2416): 676. Bibcode:1916Natur..96R.676S. doi:10.1038/096676b0. S2CID 36078913.

• Nomenclature system for X-ray spectroscopy (1991) IUPAC.