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 4p-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 À1 p À1 p à and n À2 p à states and the outermost satellites are lower than the p À2 p à state of butadiene. However, their intensities are very small, since they do not effectively interact with the main peaks. The p À2 p à state of methylenecyclopropene with constrained p-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 s18 eV.

Singly and doubly excited states of butadiene, acrolein, and glyoxal: Geometries and electronic spectra

“…The valence MOs are n + , n − , CvO −, and CvO + in the order of increasing IP experimentally proposed by Turner, 37 which is in agreement with the present SAC-CI results. The previous systematic SAC-CI study 65 on the valence shell of 4-conjugated molecules also gave the same ordering for these states. Therefore, the excitations corresponding to → * transition are relatively higher in energy than those of n → * ; the order of valence shell is important for the correct assignments of the excited states.…”

Ultrafast electron dynamics following outer-valence ionization: The impact of low-lying relaxation satellite states

“…However, numerous theoretical and experimental studies showed that there are certain classes of compounds where satellites can appear also in the outer-valence region. These are systems containing heavier atoms, like transition-metal complexes [21,22], or π-electron systems [23,24,25,26,27], which have lowenergy virtual orbitals. Here we will concentrate on the latter class of systems and will investigate the impact of the low-lying satellites on the electron dynamics following outer-valence ionization of some organic unsaturated nitroso compounds [27].…”