Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 87: Metal Substrates: Structure, Epitaxy and Growth

O 87.2: Talk

Thursday, March 10, 2016, 15:15–15:30, S053

Structural analysis of Pd on W(110) — •Jeannette Kemmer and Matthias Bode — Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany

We report on a scanning tunneling microscopy (STM) study of the thin-film growth of Palladium (Pd) on W(110). Depending on the Pd thickness various surface superstructures are observed. Sub-monolayer Pd coverages exhibit periodic stripes runing along the 001 direction of the substrate. Their periodicity amounts to (7.3 ± 0.5) nm and does not change significantly up to coverages of 0.88 atomic layers (AL). Additionally, zigzag lines appear in between the straight stripes. Atomically resolved images reveal that these stripes mark transition regions between inequivalent asymmetric Pd adsorption site, i.e. left- and right-shifted relative to the centro-symmetric hollow adsorption site usually found on bcc(110) surfaces. At Pd coverages between 0.93 AL to 1.01 AL the stripe anisotropy along the 001 direction of the substrate decrease. At the same time the stripe periodicity steeply increases, resulting in structural domain sizes up to 100 nm with right- and left-shifted adsorption sites. The second layer starts to grow on step edges and as hexagonal islands with additional stripes on top. The stripes are fully developed when the second layer is completly closed. Island growth starts with the third layer and marks the transition between the bcc crystal structure of the substrate and the fcc crystal structure of the Pd.