excitation level

in X-ray spectroscopy
X-ray levels have various degrees of @I03183@ -- single, double or higher -- and may in some cases also be electrically neutral. An excitation level (@E02258@) is an electrically neutral @X06715@ with an expelled electron bound in the field of a core electron vacancy.
PAC, 1991, 63, 735. (Nomenclature, symbols, units and their usage in spectrochemical analysis - VIII. Nomenclature system for X-ray spectroscopy (Recommendations 1991)) on page 738 [Terms] [Paper]