The electronic structure of fullerenes and fullerene compounds from high-energy spectroscopy

Abstract

The electronic structure of fullerenes and fullerene compounds from high-energy spectroscopy Golden, M.S.; Knupfer, M.; Fink, J.; Armbruster, J.F.; Cummins, T.R.; Romberg, H.A.; Roth, M.; Sing, M.; Schmidt, M. Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract The high-energy spectroscopic study of the elecuonic smcture of fullerenes and their compounds in the solid staie is reviewed. it is shown that photoemission and electron enera/-loss spectroscopy in transmission provide powerful tools for the~experimental study of the electronic structure of solid Cao, C7a and higher fullerenes. as well as the compounds formed by their intercalation wilh alkali and alkaline-earth metals. Topical issues in the field are addressed. such 3s the role played by elecmn conelmion, disorder and eleciron-phonon coupling.

Surface Hubbard U of alkali fullerides

“…The width of the first IPES structure is anomalously large compared with that of the C 60 and Cs 6 C 60 features. Such feature results from the superposition between the empty LUMO-derived states and the LUMO+1 band, which shifts non-rigidly with increasing doping [63]. A similar overlap is observed in the IPES spectrum of Rb 4 C 60 [64].…”

The electronic structure of polymerized fullerenes and dimerized heterofullerenes

“…For C 60 it has been confirmed by measuring the (q) dependence of the loss function (at high q dipole allowed transition are suppressed in favour of monopole and quadrupole transitions) that the gap transition is a dipole forbidden excitonic h u → t 1u transition at about ≈ 2 eV [29]. For the q-dependence of the o-Rb 1 C 60 polymer, we find that the very broad features in the loss function at about 2.2, 3.6, and 4.8 eV decrease with increasing q and therefore are dipole allowed.…”

“…In the inset the loss function of the Rb 1 C 60 polymer is plotted in an extended energy region of 0 to 45 eV. The two strong maxima in the loss function at about 6.4 eV and about 23 eV (slightly lower than the 25 eV maximum for C 60 ) are characteristic for sp 2 carbon systems like graphite, conducting polymers, C 60 or other fullerenes [26,27,29] and can be assigned to the socalled π plasmon (6.4 eV), reflecting the collective excitation of the π electrons, and the π + σ plasmon (23 eV), a collective excitation of all π and σ derived valence electrons, respectively. For polymerized Rb 1 C 60 the π → π* features be- tween 2 and 6 eV are significantly broadened compared to C 60 and the maxima can barely be resolved in the loss function (only very broad and weak features at 2.2, 3.6, and 4.8 eV can be observed).…”

Electron Spectroscopy Studies of Carbon Nanotubes

“…In C 60 (Fig. 4, right-hand panel) [14], four features corresponding to unoccupied π * molecular levels are present below the σ * onset at 291 eV. Finally we come to valence band excitations recorded by EELS.…”

“…The gap between the σ and the σ * band is about 9 eV and the total width of the σ bands is of the order of 40 eV. Figure 4 displays a PES spectrum of solid C 60 , which is quite different from that of graphite [14]. What is striking is the sharp and well separated features which correspond to the highly degenerate molecular levels of C 60 [15].…”