Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 15: Postersitzung (Adsorption an Oberfl
ächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Rastersondentechniken, Zeitaufgelöste Spektroskopie, Methoden)

O 15.14: Poster

Freitag, 4. März 2005, 17:00–20:00, Poster TU D

Investigation of thin hexane films using coherent X-rays — •Robert Fendt¹, Simone Streit¹, Michael Sprung^2,1, Christian Gutt^3,1, Anders Madsen⁴, and Metin Tolan¹ — ¹Experimentelle Physik 1, Universität Dortmund; Otto-Hahn-Str. 4, 44227 Dortmund, Germany — ²8ID/IMMY-XOR-CAT, APS/ANL, Argonne, IL, 60439, USA — ³Department of Physics 0350, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0350, USA — ⁴ID10A, ESRF, B.P. 220, F-38043 Grenoble, France

Very thin hexane films were prepared on a silicon substrate via condensation from a vapour phase. Using this method, it is possible to produce thin films of different thickness (about 20-200 angstroms) by changing the sample temperature. The films were first investigated by means of X-ray photon correlation spectroscopy to measure the spectrum of the capillary waves which were expected on the liquid surface. However, all XPCS measurements showed no dynamics at all on the investigated length and time scales (i.e., a few µm and 10⁻⁶ to 1000s). As a consequence, static diffuse scattering scans of the surface were made, revealing pronounced speckle structures. These speckles were proven to be stable at least on time scales of up to 20 minutes. The pattern changes slightly when changing the film thickness slowly, and very drastically after quick thickness changes. We believe that this corresponds to different growth modes of the sample on the substrate.