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O: Oberflächenphysik

O 43: Adsorption an Oberflächen IV

O 43.1: Vortrag

Freitag, 12. März 2004, 11:15–11:30, H36

Multilayer Adsorption and Wetting of Acetone on Graphite — •Frank Kruchten — Universität des Saarlandes, Technische Physik 7.3, 66123 Saarbrücken

Adsorption/desorption isotherms of acetone on highly oriented pyrolytic graphite have been measured by ellipsometry for temperatures above the bulk triple point. The behavior in the monolayer and submonolayer regime is conventional, with 2D gas-liquid and 2D liquid-solid coexistence regions. Further liquid monolayers grow on top of the completed monolayer. The growth is basically layer-by-layer. For temperatures between 190 K and the triple point a prewetting-type transition occurs with a thin-thick jump of the layer thickness on adsorption but a layer-wise removal of the film on desorption. In this temperature regime the first monolayer is solid and its molecules are oriented perpendicular to the substrate whereas the higher layers are orientationally disordered polar liquid.

This work has been supported by the Deutsche Forschungsgemeinschaft (Project No. Kn 234/9).

F.Kruchten and K.Knorr, Phys. Rev. Lett. 91, 085502 (2003)