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Researchers model atomic-scale energy exchange between gases and metal surfaces

May 07, 2012
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A theoretical model has been developed that for the first time introduces the effects on interchanging energy at an atomic scale into precise dynamic simulations in the interaction of atoms or molecules of gas with metal surfaces.

The results come from a team of scientists at the mixed CSIC-UPV/EHU Centre for the Physics of Materials (CFM) at the Donostia International Physics Center (DIPC) and the University of the Basque Country (UPV/EHU), working in collaboration with the Bariloche Atomic Centre in Argentina. Knowledge about these types of interactions has implications, the researchers say, for very different fields of applications, including the making of industrial chemicals.

The research, recently published in the Physical Review Letters journal, is an important advance in the modeling of these reactive processes. When low-energy gas atoms or molecules hit the surface of a metal, the atoms or molecules of this gas react with the surface. Knowing what happens during these reactions is important, for example, because industrial manufacture of important chemical products involves the use of metal surfaces as catalysts. Being able to simulate the dynamics of the interaction of gas/surface reactive processes with the greatest possible precision is therefore of the highest importance.

To date modeling these processes has been based on very precise simulations of molecular dynamics, but hasn’t taken into account so-called inelastic effects, i.e., electronic excitations or the vibrations of the atoms making up the metal’s crystalline network. However, recent experiments have shown the need to incorporate in simulations a description of these types of channels of energy interchange. It is precisely this that researchers at the CFM, the DIPC and the UPV/EHU have achieved, they say.

Their model incorporates these inelastic channels of energy loss and interchange between the gas and metal surfaces, while maintaining the precision of the calculations which have not included such effects hitherto. The model was applied to the study of two representative systems such as the interaction of molecules of nitrogen with the surface of tungsten and the interaction of atoms of nitrogen with silver metal surfaces, demonstrating its validity compared to the results obtained with existing experimental measures. It was able to reproduce non-trivial effects observed in the gas atoms or molecules after being reflected from the metal surfaces.

This work opens up new frontiers in the study of modeling these elemental reactions at gas/metal surface interactions, the researchers conclude, enabling quantification of the relevance of the different processes of interchanging energy.

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