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MM: Fachverband Metall- und Materialphysik
MM 12: Postersitzung I
MM 12.50: Poster
Monday, March 14, 2011, 17:30–19:00, P5
In-situ TEM investigation under extreme heat: Gold and hydrocarbon adsorbates on graphene — •Benedikt Westenfelder1, Jannik C. Meyer2, Xiaohang Lin3, Ferdinand Scholz1, Carl E. Krill III4, Axel Groß3, and Ute Kaiser2 — 1Institute of Optoelectronics, Ulm University, 89081 Ulm, Germany — 2Central Facility of Electron Microscopy, Ulm University, 89081 Ulm, Germany, — 3Institute of Theoretical Chemistry, Ulm University, 89081 Ulm, Germany — 4Institute of Micro- and Nanomaterials, Ulm University, 89081 Ulm, Germany
Atomically resolved studies of the heat-induced evolution of adsorbates on graphene have been enabled due to the development of specifically designed TEM sample carriers. Our concept provides to apply in situ an electrical current to a freestanding graphene membrane. In this way we reach local temperatures exceeding 2000 K enabling to observe the transformation of adsorbated hydrocarbons into atomic layers of amorphous carbon and eventually into polycrystalline graphene. Moreover, we observed the migration of gold nanoparticles and their self-organized alignment along parallel straight lines along the negative temperature gradient. Furthermore, we investigated the periodical arrangement of individual gold atoms into rectangularly shaped atomic monolayers and bilayers as well as entire cuboids of many atomic layers. We found, that their lattice parameter is significantly larger than the value for pure gold articles, which might be caused by the incorporation of excess carbon into the gaps of the gold fcc lattice. DFT calculations suggest that an interstitial gold-carbon compound has been developed.