Losses in the Energy of Low-Energy Electrons in Fluorene, Fluorenone, and Diiodofluorenone Vapors

Electron energy loss spectra (EELS) of fluorene, fluorenone, and diiodofluorenone vapors excited by monokinetic electrons of energies 15–50 eV have been obtained. The singlet and triplet absorption bands of these molecules have been calculated. Comparison of these bands with the experimental EELSs and optical absorption spectra has shown that the forbiddenness of singlet-triplet transitions is not completely removed in the process of interaction of molecules with electrons. The presence of heavy iodine atoms in the diiodofluorenone molecule enhances singlet-triplet transitions. Bands of overtones of stretching vibrations of the CH groups of the benzene rings have been detected near the peak of elastic scattering of electrons of the molecules studied.