Kernlinie

Kernlinie is a term used in spectroscopy to denote a spectral line arising from transitions involving the innermost electron shell of an atom, the K-shell. When a vacancy is created in the K-shell—for example by X-ray or electron irradiation—an electron from a higher shell drops into the K-shell and emits a characteristic X-ray with an energy specific to the element. These lines are commonly referred to as K-lines, with the primary types being K-alpha (L-shell to K-shell) and K-beta (M-shell to K-shell), among others.

The energy and intensity of Kernlinien depend on the atomic number and the electronic structure of the element. The energies of characteristic X-rays follow trends captured by Moseley’s law, which relates the line frequency to the atomic number. In practice, Kernlinien are used to identify and quantify elements in a sample through X-ray fluorescence (XRF) spectroscopy or related techniques. They appear in energy-dispersive or wavelength-dispersive spectra and serve as element-specific markers.

Terminology varies by field and author. In many German-language sources the lines corresponding to transitions to the K-shell are called K-Linien, and Kernlinie may be used as a synonym for these lines. In nuclear physics, the term Kernlinie may occasionally be used more broadly to refer to spectral lines from nuclear transitions, such as gamma-ray lines, though this usage is less common.

See also: K-shell, characteristic X-ray, K-alpha line, K-beta line, X-ray fluorescence, Moseley’s law.