## Rydberg transition

https://doi.org/10.1351/goldbook.R05432
An electronic transition described approximately as @P04877@ of an electron from a 'bonding' orbital to a @R05431@. Spectral bands corresponding to Rydberg transitions approximately fit the Rydberg formula: $\sigma = I - \frac{R}{(n\,-\,\mathit{\Delta })^{2}}$ where $$\sigma$$ is the wavenumber, $$I$$ the @I03208@ of the atom or molecular entity, $$n$$ a principal quantum number, $$R$$ the @R05430@, and $$\mathit{\Delta}$$ the quantum defect which differentiates between s, p, d, etc., orbitals. The notation used is, e.g. $$\pi \rightarrow \mathrm{ns}$$.
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2272 [Terms] [Paper]