Valence ionization spectra of 4π-electron molecules with low-lying satellites involving n–π* and π–π* transitions

Abstract

The valence ionization spectra up to 25–30 eV of the 4π-electron molecules, butadiene, acrolein, glyoxal, methylenecyclopropene and methylenecyclopropane were investigated by the SAC-CI method. Accurate theoretical assignments of the spectra were given and further the natures of the low-lying satellites were examined. Acrolein and glyoxal have the low-lying satellites of n⁻¹π^-1π* and n^-2π* states and the outermost satellites are lower than the π^-2π* state of butadiene. However, their intensities are very small, since they do not effectively interact with the main peaks. The π^-2π* state of methylenecyclopropene with constrained π-conjugation was calculated to be much higher than that of butadiene, though the first IP is lower. In these spectra, some split peaks were calculated at 15–16 eV and the continuous shake-up states were obtained in the region higher than ∼18 eV.

§Dedicated to Professor Michael A. Robb on the occasion of his 60th birthday.

Acknowledgements

This study has been supported by the Grant for Creative Scientific Research from the Ministry of Education, Science, Culture, and Sports of Japan.

Notes

§Dedicated to Professor Michael A. Robb on the occasion of his 60th birthday.