Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 53: Nanostructures at surfaces: Dots, particles, clusters III
O 53.2: Vortrag
Donnerstag, 26. März 2009, 15:15–15:30, SCH A215
Ag island and cluster growth and thermal stability on C60 films — •Lukas Patryarcha1, Stefanie Duffe1, Michael Moseler2,3,4, and Heinz Hövel1 — 1Technische Universität Dortmund, Experimentelle Physik I — 2Universität Freiburg, Fakultät für Physik — 3Fraunhofer-Institut für Werkstoffmechanik, Freiburg — 4Freiburger Materialforschungszentrum
In former experiments for Ag309/C60/HOPG and Ag309/C60/Au(111) a substrate dependent cluster stability was observed [1]. In order to compare with these data, here at T<50 K Ag atoms with an effective coverage of 0.5 monolayers (ML) were evaporated on Au(111) functionalized with 1.5 ML C60 and imaged with STM at 77 K. Cluster growth on 1 and 2 ML C60 was observed directly after evaporation with STM at 77 K. After 45 min at 215 K most of the clusters grown on 1 ML decayed. The atomistic calculations for Ag309/C60/Au(111) [1] suggest that Ag atoms moved through 1 ML C60 to the Au(111) surface and formed Ag monolayer islands below the C60 film. Primary clusters with a height of about 1,3 nm and 1,7 nm were formed on 2 ML C60 and stayed stable for 14 days at room temperature. In an additional experiment 4 ML Ag were evaporated. Also in this case no long-time stable clusters at T>265 K on 1 ML C60 were observed while clusters on 2 ML grew. By approximating the cluster shape with an ellipsoid a width-height-factor was calculated, so cluster growth effects and the change of the effective cluster coverage remaining on the surface after each annealing step could be identified.
[1] S. Duffe et al., submitted for publication