Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 41: Graphene III
O 41.1: Talk
Wednesday, March 28, 2012, 10:30–10:45, MA 041
Intercalation of O2 and CO on graphene grown on Ir(111) — •Elin Grånäs1, Jan Knudsen1, Timm Gerber2, Ulrike Schröder2, Mohammad Arman1, Karina Schulte3, Thomas Michely2, and Jesper Andersen1 — 1Division of Synchrotron Radiation Research, Lund University, Sweden — 2II. Physikalisches Institut, Universität zu Köln, Germany — 3MAX IV Laboratory, Lund University, Sweden
Graphene is a potential support material for catalytic model systems since it is chemically inert at room temperature and has a high thermal stability in ultra-high vacuum (UHV). The stability in a controlled gas environment at slightly elevated temperatures (300 - 500 K), typical for many catalytic processes, is however virtually unexplored. In this contribution we will discuss the stability of graphene supported on Ir(111) in common gases such as O2 and CO in the pressure interval from 10−8 to 0.1 mbar.
We find that both CO and O2 intercalate when holes are present in the graphene film, and with the use of X-ray photoemission spectroscopy movies we follow the intercalation process in real time. Surprisingly our studies reveal that intercalation of O2 and CO starts already close to room temperature. One important consequence of this is that graphene grown on transition metals often is converted to graphene floating on a layer of adsorbates when it is exposed to either O2 or CO at slightly elevated temperatures. Finally we will discuss scanning tunneling microscopy studies of the partly intercalated films, that reveal how the intercalation proceeds.