Chemistry Reference
In-Depth Information
Fig. 3.8
Schematics of the DELTA0.5 HREELS spectrometer, designed by Prof. Harald Ibach and
commercialized by SPECS
Fig. 3.9
DELTA0.5 HREELS
spectrometer, designed by
Prof. Harald Ibach and
commercialized by SPECS
The difference in bonding also reflects in the phonon modes of graphene. A
softening of the phonon modes indicating weakened C-C bonds is observed in the
case of strong binding, whereas in the case of weak binding the phonon frequencies
stay close to the bulk values known from HOPG (Benedek and Onida
1993
). The
electronic structure ranges from almost no interaction in the case of Pt(111) (Politano
2011c
) to deep a modification in the case of a graphene monolayer on Ni(111) (Wang
et al.
2011
) or Ru(0001) (Borca et al.
2009
,
2010
).
For platinum the lattice constant is
a
=
3.92
Å and the nearest neighbour dis-
tance between atoms is
d
=
2.77
Å. For graphene the lattice constant is
a
=
2.46
Å and the nearest neighbour is
d
1.42
Å. As can be seen from a comparison of
the close-packed layer of atoms of the Pt(111) surface and the honeycomb struc-
ture of graphene, they both have hexagonal symmetry. This similarity should make
Pt(111) a natural fit for growing well-ordered graphene on the surface. However, the
presence of a difference in lengths of the lattice constants, results in a mismatch of
approximately 11 %.
=
