Molecular Rydberg transitions. V. Atomic correlation lines

Abstract

It is shown, for several groups of atoms, that the term values of low‐energy Rydberg excitations are linearly correlated with the corresponding ionization potentials. The form of this relation is T (μ,α,n)/Z²=a_nαI_μ/Z²+b_nα, where T (μ,α,n) is the term value of the nth lowest‐energy Rydberg state of αth type (i.e., α is a symmetry index) derived from the μth cationic parent; I_μ is the ionization potential; Z is the core charge; and a_nα and b_nα are the correlation coefficients. A discussion of the intercepts b_nα leads to the concept of an average (or zero‐order) member of a given group of atoms and to determination of spectroscopic data for this ’’average atom.’’