Adsorption of fullerene and azafullerene on Cu(111) studied by electron energy loss spectroscopy

Fullerene and azafullerene films were studied by electron energy loss spectroscopy in reflection geometry. Compared to C60, (C59N)2 multilayers show additional vibrational modes that are characteristic of the dimer structure. The (C59N)2 is semiconductor-like and giant optically allowed excitonic transitions are found in the gap in drastic contrast with C60. The azafullerene monolayer on Cu(111) no longer shows the presence of dimers, indicating monomer adsorption. Similarly to C60, azafullerene molecules in contact with the metal substrate receive a transferred charge between two and three electrons. However, the C59N appears more covalently bound to Cu because it decomposes when heated above 660 K while C60 only desorbs.

Relativistic Calculation of two-Electron one-Photon and Hypersatellite Transition Energies for 12≤Z≤3012\leq Z\leq30 Elements

Energies of two-electron one-photon transitions from initial double K-hole states were computed using the Dirac-Fock model. The transition energies of competing processes, the K$\alpha$ hypersatellites, were also computed. The results are compared to experiment and to other theoretical calculations.Comment: accepted versio

Breakdown of the dipole approximation in core losses

The validity of the dipole approximations commonly used in the inelastic scattering theory for transmission electron microscopy is reviewed. Both experimental and numerical arguments are presented, emphasizing that the dipole approximations cause significant errors of the order of up to 25% even at small momentum transfer. This behavior is attributed mainly to non-linear contributions to the dynamic form factor due to the overlap of wave functions