Term: Rydberg orbital
https://doi.org/10.1351/goldbook.R05431

Definition:
For an atom, an orbital with principal quantum number greater than that of any occupied orbital of the ground state. For a molecular entity, a molecular orbital which correlates with a Rydberg atomic orbital in an atomic fragment produced by dissociation. Typically, the extension of the Rydberg orbital is large compared to the size of the atom or molecular entity.

Related Terms:
1) ground state (http://doi.org/10.1351/goldbook.G02704).
2) molecular orbital (http://doi.org/10.1351/goldbook.M03996).
3) dissociation (http://doi.org/10.1351/goldbook.D01801).

Source: PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2272 (https://doi.org/10.1351/pac199668122223)

Citation: 'Rydberg orbital' 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.R05431

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