Regensburg 2010 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

O: Fachverband Oberflächenphysik

O 25: Metal substrates: Adsorption of organic / bio molecules III

O 25.7: Talk

Tuesday, March 23, 2010, 12:00–12:15, H36

Planar chain structure of formic acid on Au(111) surfaces studied by Micro-Channel Plate (MCP)-LEED — •Mirko Müller, Michel Kazempoor, and Gerhard Pirug — Institut für Bio- und Nanosysteme (IBN 3) and JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

Vibrational spectroscopy (HREELS) indicates that formic acid adsorbs in a molecular reversible manner on Au(111) surfaces.(1) The vibrational signature points to the formation of flat lying chains of H-bonded formic acid molecules. This hypothesis could not be proven by structure investigations using conventional LEED systems. The electron beam sensitivity of the adsorbed layer prevents from the observation of clear LEED patterns. On the contrary bright LEED spots could be observed using a micro-channel plate (MCP) LEED system which allows a more gentle examination with reduced electron beam current in the pA regime. Consistent with the weak chemical interaction of physisorbed formic acid molecules the reconstruction of the Au(111) surface is not lifted. In addition an incommensurate rectangular superlattice could be identified. Missing (0,2n+1) spots indicates the presence of mirror glide plane symmetry p2mg consistent with the formation of zig-zag chains containing links of cis formic acid molecules oriented accordingly.

(1) M. Kazempoor, and G. Pirug, Appl. Phys. A 87, 435-441 (2007)