The second example exemplifies the use of the nanomesh pores, which
form strong confining
potentials,
for trapping molecules well
above room temperature.
Naphthalocyanine (Nc) molecules were
vapor-deposited
onto the nanomesh kept at room temperature.
These planar molecules have a diameter of about 2
nm, what means that their size is comparable to that of the
nanomesh pores (see lower inset).
On the STM image on the right it is spectacularly visible how the molecules form a well-ordered array
with the periodicity of the nanomesh (3.22
nm).
The upper inset shows a region of this
substrate with higher resolution.
Individual molecules are trapped inside the pores, what indicates a highly site selective
adsorption.
The interactions between the Nc molecules and the nanomesh dominate the
adsorption behavior and
interactions between Nc molecules are weak. This behavior is in contrast to Nc on flat
graphite for example.
The strength of the trapping potential for Nc is quite strong since only rare hopping events could
be observed at room temperature. Annealing to 650K does also not lead to
desorption
of the molecules from
the pores.