excitation level 

in X-ray spectroscopy
https://doi.org/10.1351/goldbook.E02252
X-ray levels have various degrees of ionization -- single, double or higher -- and may in some cases also be electrically neutral. An excitation level (exciton) is an electrically neutral X-ray level with an expelled electron bound in the field of a core electron vacancy.
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 738 [Terms] [Paper]
Citation: 'excitation level' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.E02252 RIS BibTex EndNote
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Last revised: February 24, 2014