Dresden 2006 – scientific programme
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O: Oberflächenphysik
O 9: Organic films I
O 9.1: Talk
Monday, March 27, 2006, 15:00–15:15, TRE Phys
STM and LEED studies of α-sexithiophene on Au(111) — •Mario Kiel, Klaus Duncker, Christian Hagendorf, and Wolf Widdra — Martin-Luther-Universität Halle-Wittenberg, FB Physik, D-06120 Halle(Saale)
The growth of α-sexithiophene (6T) on the close-packed Au(111) surface has been studied by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). The evaporation of the 6T molecules from a home-built Knudsen cell and measurements have been performed at a base pressure of 1× 10−10 mbar. STM images reveal rows of equivalent 6T molecules with one molecule per unit cell. The rows are rotated by 9∘ with respect to the [112] direction and span large Au(111) terraces (∼100 nm). Six symmetry-equivalent domains are possible, however step-induced structures with the molecular axis along the step edges are strongly favored. This can be also seen by higher spot intensities in LEED, visible due to a small crystal miscut. On the terrace, the herring bone (22×√3) reconstruction of the clean Au(111) surface is stretched by about 15% upon 6T monolayer adsorption. This is interpreted as adsorbate-induced strain in the first Au(111) layer.