Interelectronic-state perturbation effects on photoelectron spectra and emission quantum yields

Abstract

Model calculations are carried out on the photoelectron and ion emission spectra of a hypothetical diatomic molecule in the absence and presence of intramolecular coupling between two emitting excited states B ⁺ and A ⁺ of the ion. We show that interelectronic state coupling has relatively little influence on the frequency distribution of the photoelectron spectrum while modifying considerably the optical emission spectrum. Shifts of intensity from apparent B ⁺ to apparent A ⁺ emission spectral regions are shown to occur. This result explains the observation of apparent state quantum yields different from unity for emission from [Btilde] ²Σ _u ⁺ and à ²Π _u states of CO₂ ⁺, as well as the discrepancy between apparent populations of these two excited states inferred from photoelectron and emission spectral intensities.

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William M. Gelbart

Alfred P. Sloan Foundation Fellow and Camille and Henry Dreyfus Foundation Teacher-Scholar. Present address 1977–78 : Laboratoire de Photophysique Moléculaire, Bˆatiment 213, Université Paris-Sud, 91405, Orsay, France.