Siegbahn notation

The X-ray photons emitted by excitation of a shell X form the X series. In a given series, the lines arc ranked using Greek letters with indices in decreasing order of intensity (Siegbahn notation). 

X-ray wavelengths in A units and in keV. The probable error (p.e.) is the error in the last digit of wavelength. Designation indicates both conventional Siegbahn notation (if pUcable) and transition, e.g., Pi LuMiw denotes a transition between the Lu and Mr levels, which is the LPi line in Siegbahn notation. 

Note. Not all lines are seen for all elements, and many of the Unes are not resolved with standard X-ray spectrometers. Many M M, N M, O —> L, and O M transitions have no Siegbahn notation associated with them. 

Table 11.1 Principal X-ray lines (lUPAC and Siegbahn notations) and their approximate intensities relative to the major line in each subshell.

The electronic structure of the atoms is specific to each element in the periodic table. This describes the distribution in energy and space of stationary states (levels in which electrons can reside). These states are described using spectroscopic or X-ray notation (these both describe the same thing), whereas ttansitions can be described via one of the above two notations, or the Siegbahn notation (for historical reasons, this depends on the outcome). Electrons in these stationary states are described by a specific set of quantum numbers, with no two electrons from the same atom being allowed to share the same quantum numbers. Free electrons are not ascribed a set of quantum numbers. 

The selection rules applicable to optical dipole transitions also apply to X-ray transitions. The rules are AL = 1, Aj = 0, 1. Intensity rules are also the same as those applicable to optical transitions. The transitions obeying selection rules are called normal transitions. Not all transitions allowed by selection rules are observed. On the contrary, some transitions, which are not allowed by selection rules, are sometimes observed. These are called forbidden transitions. The observed lines were initially given names as per their observed line intensities. The Siegbahn notation used to name various observed lines is given in Table 1. As this nomenclature is intensity-based... 

Table 1 Siegbahn notation for various inner shell X-ray transitions...

The intensities give the emission probabilities for 100 vacancies in the K shell. In the first column the initial and final shell vacancy together with the classical Siegbahn notation is given. The listed intensities are based on the emission probabilities compiled by Seel-mann-Eggebert etal. [47] and on the atomic yields published by Krause [46]. The energies were calculated from the data published by Larkins [21]. 

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