resonance fluorescence

https://doi.org/10.1351/goldbook.R05335
@[email protected] from the primary excited atomic or molecular species at the @[email protected] of the exciting radiation (no @[email protected] within the excited manifold). This term is also used to designate the radiation emitted by an atom of the same @[email protected] as the longest one capable of exciting its @[email protected], e.g. \(122.6\ \text{nm}\) in the case of the hydrogen atom, and \(253.7\ \text{nm}\) in the case of the mercury atom.
See also:
resonance line (in photochemistry)
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2271 [Terms] [Paper]