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O: Fachverband Oberflächenphysik
O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)
O 60.16: Poster
Mittwoch, 16. März 2011, 17:30–21:00, P4
C2 inclusion by C60 in thin films deposited on HOPG — Seyithan Ulas, Dmitry Strelnikov, Daniel Löffler, Patrick Weis, •Artur Böttcher, and Manfred M. Kappes — Karlsruher Institut für Technologie, Institut für Physikalische Chemie, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
The deposition of hyperthermal C2− anions onto C60 films has been studied by means of mass spectrometry, thermal desorption spectroscopy (MS), ultraviolet photoionization spectroscopy (UPS), atomic force microscopy (AFM) and Raman spectroscopy. The inclusion of C2 dimers by C60 cages manifests itself by the sublimation of the C62, C64 and C66 cages as well as by pronounced modifications of the thermal, electronic and vibronic properties of the C60 films. The most efficient reaction channel: the formation of volatile C62 species depends on the deposition conditions. Its yield, y(C62), does not overcome 10−2 per C2. UPS and Raman spectra of the C2/C60 layers supported by DFT calculations indicate the formation of polymeric network based on -C60-C2-C60- chains as well as C62 (and -C62-C62- chains) as two prevailing inclusion channels. Thermal desorption spectra reveal coherent sublimation of C60 and C62 what implies that thermal decomposition of the -C60-C2-C60- oligomeric chains is the common dissociative reaction step. In temperature range 750 - 975 K the thermal decomposition of the -C60-C2-C60- oligomeric chains competes with the thermally activated inclusion of the C2 into C60 cages resulting in non-IPR C62 cages arranged in semiconducting network. At higher temperatures the network becomes converted predominantly into conducting carbon chains of fused C62 cages.