resonance line

in X-ray spectroscopy
Also contains definition of: resonance emission
https://doi.org/10.1351/goldbook.R05341
The radiative decay of an excitation level may proceed to the neutral @[email protected] and would thus occur at the same energy as the corresponding line in the @[email protected] Such a line is called a @[email protected] line and the process is called resonance emission.
Source:
PAC, 1991, 63, 735. (Nomenclature, symbols, units and their usage in spectrochemical analysis - VIII. Nomenclature system for X-ray spectroscopy (Recommendations 1991)) on page 739 [Terms] [Paper]