Solid Interfaces

Phase Transitions and Transport Phenomena in Thin Films at Solid/Air Interfaces

1.) Local interfacial properties (roughness, chemical composition, etc.) influence the heterogeneous nucleation and growth of small aggregates at surfaces. This is well accepted, but quantitative experimental studies are virtually non-existing. We investigate by AFM the impact of artificial, nanometer size morphological surface modifications on the nucleation and growth of fullerene (C60) aggregates from supersaturated solutions (Fig. 1a). We also measured the line tension τ (≈-10-11N) of sessile C60 droplets/aggregates (Fig. 1b) that transform with increasing volume - because of the negative τ - from 2-dimensional domains into sessile droplets.

Fig. 1a: Influence of indentations in SiO2 surfaces (depth <2nm!) on the location and growth of C60 aggregates.


Fig. 1b: Contact angle as function of the curvature of the surface contact area (α inverse of droplet size) of C60 aggregates on SiO2. The cartoon shows the variation of the aggregate shape with increasing volume.


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