The Photoelectron Spectrum of Tetrafluorobutatriene

The He(I_α) and He(II_α) spectra of tetrafluorobutatriene 3(F) have been recorded for comparison with those of butatriene 3(H). Ab initio double‐zeta basis self‐consistent field (SCF) and configuration interaction calculations on butatriene show that, contrary to previous assignment, no shake‐up band is expected to appear in the 9–10 eV energy range of the photoelectron spectrum. Further, such SCF calculations on tetrafluorobutatriene support the use of the perfluoro effect in assigning the purely π orbital ionizations. It is argued that 3(F) is a key compound for the study of the perfluoro effect. This is supported by a qualitative comparison of its photoelectron‐spectroscopic results with those of other perfluoro systems.