S 2p photoabsorption of the SF5CF3 molecule: Experiment, theory and comparison with SF6

The S 2p core excitation spectrum of the SF5CF3 molecule has been measured in the total ion yield mode. It resembles a lot the analogous spectrum of SF6, also recorded in this study, displaying intense transitions to the empty molecular orbitals both below and above the S 2p ionization potential (IP) and weak transitions to the Rydberg orbitals. The S 2p photoabsorption spectra of SF6 and SF5CF3 have been calculated using time-dependent density functional theory, whereby the spin–orbit coupling was included for the transitions below the S 2p IP. The agreement between experiment and theory is good for both molecules, which allows us to assign the main S 2p absorption features in SF5CF3

Resonant vibrational excitation of furan by low energy electron impact

Our purpose was to investigate the resonant vibrational excitation of furan (C4H4O) in its electronic ground state by electron collisions. The electron energy loss measurements have been carried out at intermediate and low impact energies for a scattering angle of 30°. The spectra show peaks or groups of peaks corresponding to the excitation of the fundamental normal modes as also of the first harmonics and combinations. The energy dependence curve for the excitation of the C-H stretching vibrational modes is also reported for the impact energy range of 3-10 eV. It exhibits a broad structureless band with a maximum centered around 6 eV, which reveals an excitation mechanism through the intermediate of a shape resonance built on the electronic ground state of the neutral molecule. A comparison with benzene is made in order to help the analysis and to assign the nature as well as the symmetry of the resonance. © 1996 American Institute of Physics