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O: Fachverband Oberflächenphysik

O 35: Nanostructures at Surfaces

O 35.12: Poster

Dienstag, 17. März 2015, 18:15–21:00, Poster A

Scanning photoelectron microscopy of high-temperature-Cs_xC₆₈ — •Jürgen Weippert¹, Seyithan Ulas¹, Sharali Malik², Matteo Amati³, Luca Gregoratti³, Maya Kiskinova³, and Artur Böttcher¹ — ¹Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany — ²Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany — ³ESCA microscopy beamline Elettra - Sincrotrone Trieste, ScPA Area Science Park, 34149 Basovizza-Trieste, Italy

Surface morphology of the non-IPR fulleride Cs_xC₆₈ grown via co-depositing Cs and mass-selected C₆₈⁺ in UHV has been studied by scanning photoelectron microscopy (Escamicroscopy). Cs_xC₆₈ survives heating up to T^*≈ 1000 K and shows a high thermal stability (related IPR fullerides: decomp. ≈800 K). The C1s- and Cs4d-based images revealed Cs-rich islands as striking species surrounded by planar Cs-poor areas. The islands are created by thermally activated segregation of Cs atoms emerging from the subsurface region. Whereas C1s and Cs4d XP spectra taken from the Cs-poor regions show ionic bonds stabilizing the Cs_x^+aC₆₈^−b compound the chemical state of the elements constituting the Cs-rich islands has no comparable examples in the literature of -C-Cs bonds. The islands are photoactive: Initially Cs4d band exhibits four components (69−81 eV), and C1s band consists of two components (281−286 eV). This structure evolves under illumination (hv ≈ 500 eV) towards the pattern of ionic -C-Cs bonds.