Energy-dependent vibrational excitation by electron impact in thin films of amorphous benzene

Abstract

The vibrational excitation of 10-layer films of amorphous solid benzene has been measured by electron-energy-loss spectroscopy at various incident energies between 1.2 and 14.7 eV. The high resolution of the spectra in connection with the energy dependence leads to a comprising assignment of the observed bands. The 2B 2g shape resonance is located between 3.2 and 4.2 eV which is about 1 eV lower than in gaseous benzene. The 2E 2u resonance is shifted to energies lower than 1.2 eV and is therefore not detected. The e 2u vibration, the excitation of which was previously discussed only through the 2E 2u resonance channel, is observed at all impact energies.