On-ball Doping of Fullerenes: The Electronic Structureof C59N Dimers from Experiment and Theory

We present the first studies of the electronic structure of the heterofullerene (C59N)2 using electron energy-loss spectroscopy in transmission, photoemission spectroscopy and density functional theory-based calculations. Both the C1s excitation spectra and valence band photoemission show negligible occupation of the C-derived lowest unoccupied electronic states and indicate localization of the excess electrons at the N atoms. The N1s excitation spectrum is used as an ideal local probe of the chemical environment at the N site of the heterofullerene, and comparison of these data with the C1s excitation spectrum reveals the relatively low degree of mixing between the N- and C-derived electronic states. The experimental results, together with the detailed analysis of our theoretical data, provide compelling evidence for the chemical picture of a triply co-ordinated N atom with a lone pair in each heterofullerene unit, and confirm the theoretically predicted `6,6 closed' structure for the dimer. In addition, we point out the similarities and differences between the heterofullerene dimer and the isostructural dimerized phase of Rb(1)C(60).

By: Thomas Pichler (IFW, Germany), Martin Knupfer (IFW, Germany), Mark S. Golden (IFW, Germany), Stefan Haffner (IFW, Germany), Rainer Friedlein (IFW, Germany), Joerg Fink (IFW, Germany), Wanda Andreoni, Alessandro Curioni, Majid Keshavarz-K (UC Santa Barbara), Cheryl Bellavia-Lund (UC Santa Barbara), Angela Sastre (UC Santa Barbara), Jan-Cornelius Hummelen (UC Santa Barbara) and Fred Wudl (UC Santa Barbara)

Published in: Physical Review Letters, volume 78, (no 22), pages 4249-52 in 1997

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