Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 78: Metal substrates: Adsorption of organic / bio molecules IV
O 78.4: Vortrag
Donnerstag, 29. März 2012, 16:45–17:00, A 053
Theoretical Insight into the Growth Mechanisms of 6P Monolayers on Copper Substrates — •Giulio Biddau1, Peter Puschnig1, Margareta Wagner2, Stephen Berkebile2, Alexander Fleming2, Falko Netzer2, Michael Ramsey2, and Claudia Ambrosch-Draxl1 — 1Chair of Atomistic Modelling and Design of Materials, Montauniversitaet Leoben, Austria — 2Institute of Physics, Surface and Interface Physics, Karl-Franzens University, Graz, Austria
We present a multi-technique study of the deposition and adsorption of para-sexiphenyl (p-6P) on the Cu(110) substrate and of its first monolayer (1ML) growth at high coverage, while at low coverages the adsorbed molecules repel forming a dense wetting monolayer. The characterization has been carried out by low-temperature STM experiments and Density Functional Theory calculations, performed using the generalized gradient approximation and considering van der Waals interactions with the DFT-D2 approach.Insight in the diffusion barriers is obtained by the Nudged Elastic Band method and the comparison with experimental STM results carried out with the Tersoff-Hamann approximation.We show that island growth occurs through diffusion of admolecules deposited in the second monolayer along [110] directions in a 2D Frank-van-der-Merwe layer by layer behavior.We show that molecules of the 1ML, efficiently screen the interaction of 2ML molecules with the metallic substrate.Thus,the weakly bound 2ML admolecules are allowed to diffuse with low Ehrlich-Schwoebel barrier along [110],favoring the formation a high-density reconstruction.