Bulk electronic structure ofK3C60as revealed by soft x-rays

Abstract

Bulk electronic structure of K3C60 as revealed by soft x-rays Käämbre, Tanel; Schiessling, Joachim; Kjeldgaard, Lisbeth; Qian, Limin; Marenne, Ingrid; O'Shea, James N.; Schnadt, Joachim; Nordlund, Dennis; Glover, Chris J.; Rubensson, JanErik Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. We present C 1s x-ray absorption, x-ray emission, and resonant inelastic x-ray scattering ͑RIXS͒ spectra of single-phase crystalline K 3 C 60 . The comparison to valence-band photoelectron spectra from the same sample facilitates identification of the contribution from surface and bulk electronic states in the latter. Bulk-sensitive techniques show that the valence bands of K 3 C 60 and pure C 60 are characterized by spectral features of similar width, in agreement with the predictions of band-structure calculations. Symmetry selectivity in the RIXS process allows us to assign peaks in the C 1s absorption spectrum, demonstrating a close correspondence with pure C 60 also in the conduction band. The symmetry selectivity is as pronounced in K 3 C 60 as in pure C 60 , indicating that the local C 60 symmetry is not appreciably affected by the K doping, either in the ground state or intermediate state, on the time scale of 6 fs.

Electron-hole correlation effects in core-level spectroscopy probed by the resonant inelastic soft x-ray scattering map of C60

“…The non-resonant XES spectrum of C 60 is shown as Fig. 1(c) and is in accordance with earlier published spectra, 8,13,[21][22][23][24] albeit with significantly enhanced signal-to-noise-ratio. By comparison with the calculations we find that the emission from the HOMO and the HOMO-1/-2 orbitals gives rise to two wellseparated peaks (A at 282.6 eV and B at 281.4 eV), while the other features of the spectrum, each contain a larger number of molecular orbitals.…”

“…[4][5][6][7] In the case of C 60 , which has been repeatedly studied by XAS (Ref. [8][9][10][11][12][13] and which will serve as our model system here, however, there exists a long-standing controversy about the importance of core-excitonic effects in the XAS spectra a) Author to whom correspondence should be addressed. Electronic mail:…”

Hybridization‐Induced Carrier Localization at the C60/ZnO Interface

“…When comparing this spectrum to the XAS of 1 ML C 60 on peALD ZnO (Figure B), some differences are immediately evident: at the interface with ZnO, the LUMO+ n shift to lower energies, the LUMO+2 merges somewhat with the LUMO+1, and all three unoccupied levels (LUMO, LUMO+1, LUMO+2) broaden. Such changes have also been reported in the case of alkali‐doped C 60 films, with XAS peaks progressively shifting to lower energies and broadening as a function of potassium doping in K x C 60 . The spectral changes between bulk C 60 and 1 ML C 60 /ZnO offer thus a first indication of hybridization at the C 60 /ZnO interface, likely accompanied by ground‐state charge transfer from ZnO to C 60 .…”

“…We start by discussing the XAS of several different C 60 /ZnO interfaces. Figure A (left panel) shows the C K‐edge X‐ray absorption spectrum for ≈15 monolayers of C 60 on peALD ZnO, recorded at an incidence angle of 20° and representing the well‐known C K‐edge XA‐spectrum of solid C 60 . The first four sharp absorption peaks are assigned to the excitations from the C 1s core level to individual excited states, labeled LUMO, LUMO+1, LUMO+2, and LUMO+3.…”

Multiconfigurational Study of the Electronic Structure of Negatively Charged Fullerens

“…It is known from experiment that the crystals constructed from molecules can be doped by alkali metals and form (n = 1-6, A = Na, K, Cs) crystals. Depending on the composition and the crystal structure, these crystals can be either metals or insulators [12]. For example, a compound with the same composition can be metallic in f.c.c.…”