Formation of electronically excited states in ultrathin Alq3 films during electron bombardment

Abstract

Electronic and vibrational electron energy loss spectra are studied on ultrathin Alq3 films for different electron energies, thicknesses, and temperatures of the film. The shape of the spectrum and the position of the lines are very weakly dependent on the film thickness, indicating weak interaction between the adsorbed molecules and the platinum substrate. The temperature dependence of the vibrational bands is weak. The positions of the triplet and singlet maxima are close to gas-phase and thin-film data obtained for high electron energy. Interference of electrons is observed in measuring the energy loss spectra. The effect of dipole and collisional excitation mechanisms is shown. From the similarity between the energy loss spectra it follows that the nature of the interaction between low-energy electrons and organic materials is the same in gas and thin-film phases, and likewise for the characteristics of the motion of the electrons.