Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 29: Metal substrates: Adsorption of organic / bio molecules II
O 29.4: Talk
Tuesday, March 27, 2012, 11:15–11:30, MA 043
Growth mode of formic acid on Au(111) surfaces — Christa Elsaesser1,2, Mirko Müller1,2, Christian Wagner1,2, and •Gerhard Pirug1,2 — 1Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich GmbH, 52425 Jülich — 2JARA-Fundamentals of Future Information Technology
The adsorption of formic acid (HCOOH) on a Au(111) surface has already been characterized by vibrational spectroscopy and electron diffraction using HREELS and LEED, respectively. The vibrational signature indicates weak chemical substrate interaction of flat lying chains of H-bonded HCOOH molecules1 well ordered in a (
| 1.9 | −0.3 |
| 1.7 | 2.7 |
) surface structure, as shown by LEED. The formation of ß-chains, as identified in crystalline formic acid and proposed from the pg glide mirror plane symmetry in the LEED pattern could be proven by topographical STM images. The rectangular 6.0 x 6.8 Å2 unit cell, azimuthally rotated by 8.3∘ with respect to the [110] substrate direction could be attributed to a line-on-line epitaxial growth mode2. This result is generally not expected on a (111)-oriented metal surface. While the intermolecular interaction due to H-bonding within the adsorbed layer results in a bulk-like periodic surface structure, the comparably weak adsorbate substrate interaction leads to its azimuthal alignment.
1 M. Kazempoor, and G. Pirug, Appl. Phys. A 87, 435-441 (2007)
2 S. C. B. Mannsfeld, K. Leo, and T. Fritz, Phys. Rev. Lett. 94, 056104
(2005)