- K-alpha
energy between the electron spin and the orbital momentum of the 2p orbital. K-alpha is typically by far the strongest X-ray spectral line for an element bombarded with energy sufficient to cause maximally intense X-ray emission.
The analogous K-alpha spectra line in hydrogen is known as
Lyman alpha ; however because of hydrogen's small nuclear charge, this line is in the ultraviolet, not the X-ray range. SeeSiegbahn notation for the newerIUPAC -recommended spectral notation system.An example of K-alpha lines are those seen for iron as iron atoms radiating X-rays spiralling into a
black hole at the center of a galaxy [http://arxiv.org/abs/astro-ph/0405337] . For such purposes, the frequency of the line is adequately calculated to 2-digit accuracy by the use ofMoseley's law . This formula is 10.2 eV multiplied by the square of a quantity one less than the atomic number of the element in question (atomic number minus 1). For example, K-alpha for iron (Z = 26) is calculated in this fashion as 10.2 eV (25)2 = 6.38 keV. For astrophysical purposes, Doppler and other effects (such as gravitational broadening) show the iron line to no better accuracy than 6.4 keV. [http://www.journals.uchicago.edu/cgi-bin/resolve?id=doi:10.1086/340992&erFrom=-6703307617883835216Guest]
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