Surface acoustic waves (SAW) allow to manipulate surfaces with potential applications in catalysis,s ensor and nanotechnology.SAWswere shown to cause astrong increase in catalytic activity and selectivity in many oxidation and decomposition reactions on metallic and oxidic catalysts. However,t he promotion mechanism has not been unambiguously identified. Using stroboscopic X-ray photoelectron spectro-microscopy, we were able to evidence as ub-nanosecond work function change during propagation of 500 MHz SAWs on a9nm thick platinum film. We quantify the work function change to 455 meV.S uch as mall variation rules out that electronic effects due to elastic deformation (strain) play am ajor role in the SAW-induced promotion of catalysis.I n asecond set of experiments,SAW-induced intermixing of afive monolayers thick Rh film on top of polycrystalline platinum was demonstrated to be due to enhanced thermal diffusion caused by an increase of the surface temperature by about 75 K when SAWs were excited. Reversible surface structural changes are suggested to be am ajor cause for catalytic promotion.
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The mechanism of catalytic activation … … by surface acoustic waves (SAWs) is investigated by R. Imbihl and co-workers in their Research Article on page 20224. An increase in catalytic activity of metal surfaces upon SAW excitation has been reported in numerous experiments, but the underlying mechanism needs yet to be identified. Possible causes such as SAW-induced surface restructuring and work function changes are systematically examined.
Der Mechanismus der katalytischen Aktivierung … … durch akustische Oberflächenwellen (SAWs) wird von R. Imbihl et al. im Forschungsartikel auf S. 20399 untersucht. Ein Anstieg der katalytischen Aktivität von Metalloberflächen bei SAW-Anregung wurde in zahlreichen Experimenten beobachtet, der zugrundeliegende Mechanismus konnte aber noch nicht identifiziert werden. Mçgliche Ursachen, wie z. B. SAW-induzierte Oberflächenrestrukturierung und ¾nderungen der Arbeitsfunktion, werden systematisch erforscht.
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