Spektromikroskopische Untersuchungen an ... - OPUS Würzburg

terraces than on steps and step bunches. The influence of both growth modes
is explained by the high mobility of the molecules. The high degree of lateral
order reflects in quite large domains. On Ag(111) the PTCDA-monolayer is bound
chemisorptive whereas it is bound physisorptive on Au(111). The latter also holds
true for the multilayers of both systems.
For NTCDA on Ag(111) the growth of the relaxed monolayer and the phase transition
towards the compressed monolayer could be observed directly. Within both
monolayers the molecules are oriented parallel to the substrate surface. The following
bilayer is metastable for substrate temperatures above room temperature
and is observed under continuous molecular flux only. For this bilayer an average
tilt angle of about 45° against the substrate surface was found for the molecules.
The three dimensional islands which are growing subsequent to the bilayer show
different orientations and form quite large single domains. This growth of domains
in the scale of micrometers can be explained by a bulk-like structure of the three
dimensional islands. Based on laterally resolved NEXAFS- and LEED-experiments,
a structure model is suggested which could explain the data with only one structure.
However, it was not possible within this work to finally clarify whether there is only
one structure (seen under different angles) or a mixture of more than one of them.
On both surfaces the molecules show a rather high mobility revealing a rather weak
lateral corrugation of the vertical potential.