Ab initio assignment of the UV spectra of the ethyl, isopropyl, and t-butyl radicals

Ab initio SCF and CI calculations are used to assign the UV spectra of a series of alkyl radicals. Contrary to earlier speculation, the low-lying states are shown to be predominantly Rydberg in character. The spectra of the methyl, ethyl, isopropyl, and t-butyl radicals are found to be successively red shifted in accordance with the trend observed in their ionization potentials. The nature of the first valence transition in this series of radicals is also investigated and its transition energy placed relative to the Rydberg transitions. © 1984 American Institute of Physics.