Reactive diffusion under Laplace tension

Nanostructures such as nanospheres or nanowires may contain surfaces and interfaces of pronounced curvature. To investigate the impact of severe curvature on the kinetic of reactions, thin-film Al/Cu/Al and Cu/Al/Cu triple layers are deposited on tungsten tips of 25 nm curvature radius. The thermal reaction of the layer structure is studied by atom probe tomography. Experiments demonstrate that the reaction rate depends significantly on the deposition sequence of metals. Interpretation of the observed reaction kinetics leads to the conclusion that under the influence of interfacial tension probably the two limiting cases of atomic transport, Darken and Nernst-Planck kinetics, are realized in dependence on the stacking sequence.