Shedding light on graphene using x – rays
Alessandro Baraldi,
ELETTRA Sincrotrone Trieste
17:00 - 18:00 Tuesday 20 April 2010 KFU HS 05.01 The rising interest of the scientific community in graphene is motivated by its special
and unique physical properties which make it one of the most promising materials for
applications in nano-electronics, electrochemistry and gas-sensing. Its growth by
means of hydrocarbon dissociation on transition metal surfaces represents a
challenging way to its artificial synthesis.
In this talk I will show our recent achievement on this system obtained by employing
high-resolution core level photoelectron spectroscopy with synchrotron radiation. This
method has proven to be a powerful approach to understand the peculiar growth
mechanism of a long-range ordered graphene layer on Ir(111). We have shown that,
in the initial stage, the carbon nanoislands assume a peculiar domelike shape, which
represents an intermediate phase between the strongly coupled carbidic carbon and
a quasi-free-standing graphene layer [1].
On the same system we observed a sizeable band-like dispersion of the C 1s core
level in graphene. The dispersion is observed as an emission-angle-dependent
binding-energy modulation and it is shown that under appropriate conditions only the
bonding or antibonding states can be observed [2].
Finally we have used the moiré corrugation of the graphene layer to grow metal
nanoclusters (Rh, Pt and Au) which form highly ordered superlattices with a very
narrow distribution of cluster size.
[1] P. Lacovig, M. Pozzo, D. Alfè, P. Vilmercati, A. Baraldi and S. Lizzit, Growth of dome-shaped carbon
nanoislands on Ir(111): the intermediate between carbidic clusters and quasi free-standing graphene, Phys.
Rev. Lett. 103, 166101 (2009).
[2] S. Lizzit, G. Zampieri, L. Petaccia, R. Larciprete, P. Lacovig, E.D.L. Rienks, G. Bihlmayer, A. Baraldi, and Ph.
Hofmann, Band dispersion in the deep 1s core levels of graphene, Nature Physics DOI: 10.1038/NPHYS1615.
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