Rydberg levels in CH2and CH3

Abstract

A study is made of the Rydberg levels in CH₂ and CH₃ which are associated with the outer electron in a carbon 3d-orbital. A preliminary discussion of some Rydberg states in the lithium atom showed that penetration and exchange effects between the Rydberg orbital and the core were of comparable magnitude, and strongly dependent on the correct form of the Rydberg orbital wave function in the region where this overlaps the core. In the cases of CH₃ and CH₂ some conclusions of G. Herzberg about the symmetry of excited states where a 3d-orbital is involved have been confirmed, and certain other ionization potentials estimated. In CH₂ spin-orbit forces were included, but comparison with experiment is limited. The need to orthogonalize the Rydberg orbital to any core orbitals of similar overall symmetry, and to allow mixing with other orbitals (e.g. carbon 3s with carbon 3d₀) is stressed. One of the chief causes of error at present is our ignorance about the degree of validity of Koopman's theorem for situations of this kind. It is important to know to what extent the core changes its charge distribution after the ejection of the Rydberg electron.