Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)
O 44.78: Poster
Mittwoch, 28. März 2007, 17:00–19:30, Poster C
Enhanced sensitivity and long-term stability for surface stress measurements — •Friedrich Klasing, Peter Kury, and Michael Horn-von Hoegen — University of Duisburg-Essen, Institute for Experimental Physics
Surface stress is one of the most important physical quantities determining the surface structure and morphology due to its large contribution to the total energy. Unfortunately, a direct measurement of surface stress is not possible, but it can be determined via the elastic response of a thin substrate as utilized in bending sample techniques like surface stress induced optical deflection (SSIOD) [1]. A sensitivity of the order of 0.5 Nm−1 can easily be achieved, to some extend even with commercially available tools [2].
A strongly enhanced sensitivity down to 0.005 Nm−1 (corresponding to stress effects induced by less than a percent of an adsorbate monolayer) together with a long-term stability on a time scale of one hour is only possible with extensive modifications. Still, long-term measurements over several hours suffer under drift effects caused by laser instabilities, ambient air motion and even minor detector nonlinearities. The influence of these effects on the surface stress signal drift is discussed and modifications are presented to reduce the typical drift to below 0.1 Nm−1hour−1.
[1]: A. Schell-Sorokin et al., Phys. Rev. Lett. 64(9), 1039 (1990)
[2]: http://www.k-space.com/HTML/Products/mos/
[3]: P. Kury et al., Rev. Sci. Instrum., 76(2), 023903 (2005)