Dresden 2009 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 35: Poster Session II
MM 35.21: Poster
Wednesday, March 25, 2009, 16:30–18:30, P4
Line stress from step edges and its impact on cantilever bending — •Weina Li1,2, Huiling Duan2, Maxim Smetanin1, and Jörg Weissmüller1,3 — 1Forschungszentrum Karlsruhe, Institut für Nanotechnologie, Karlsruhe — 2Peking University,Beijing,P.R.China — 3Universität Des Saarlandes, Saarbrucken
It is well known that the surface of a solid exerts a mechanical force on the underlying volume phase. This force has important ramifications for the behaviour of nanoscale objects. It is quantified by the surface stress, the derivative of a suitably defined surface excess free energy function with respect to the projection of the bulk strain tensor onto the local tangent plane. By analogy, the line elements at solid surfaces, such as triple lines, edges, or steps may also interact mechanically with the bulk. The relevant forces may be derived by taking the derivative of the line tension - an excess in energy per line length - with respect to the strain. Dimensional considerations might suggest that the line stress will emerge as a vector directed along the local line orientation. Yet, it is well known that parallel step edges interact by lateral dipole forces, so that a more general state of stress may be associated with line elements on a surface. Cantilever bending experiments provide sensitive probes for changes in the elastic interaction of the matter at the surface of a solid with the bulk. We discuss how the presence of step edges impacts the bending of cantilevers. Of particular interest are changes in the bending, either due to the creation of steps or due to the change in line stress during electrochemical cycles or reversible adsorption.