5 research outputs found
Late growth stages and post-growth diffusion in organic epitaxy: PTCDA on Ag(111)
The late growth stages and the post-growth diffusion of crystalline organic
thin films have been investigated for 3,4,9,10-perylenetetracarboxylic
dianhydride (PTCDA) on Ag(111), a model system in organic epitaxy. In situ
x-ray measurements at the anti-Bragg point during the growth show intensity
oscillations followed by a time-independent intensity which is independent of
the growth temperature. At T > 350 K, the intensity increases after growth up
to a temperature-dependent saturation value due to a post-growth diffusion
process. The time-independent intensity and the subsequent intensity recovery
have been reproduced by models based on the morphology change as a function of
the growth temperature. The morphology found after the post-growth diffusion
processes has been studied by specular rod measurements.Comment: 9 pages, 8 figures, accepted for publication in Surface Scienc
Influence of star-like iridium complexes in the graphoepitaxy of polyfluorene thin films.
We report on the impact on the equatorial and meridional orientation in hairy-rod poly[9,9-bis(2-ethylhexyl)-fluorene-2,7-diyl] thin films when blended with tris-cyclometalated oligo-fluorenylpyridine iridium(III) complex. The presence of this transition-metal complex does not alter the underlying helical motif of the polymer chain or the hexagonal unit-cell intermolecular packing. However, systematic changes in the resulting texture patterning of the crystallites are observed. Crystallites with two preferred a-b orientations, so called type I and II and differing by 30 degrees, are superimposed on an isotropic background that is designated as type III. The extent of meridional alignment for all three is found to be similar