Strong metal-support interactions definition

Thus, the spectroscopic work proved that the two forms of adsorbed hydrogen are very different. The weakly adsorbed form is definitely adsorbed above the Pt surface plane and so able to interact with the solution. In contrast, the strongly adsorbed form cannot interact with the solution, lying in the plane of the surface Pt atoms with its electron in the conduction band of the metal. This conclusion was supported by work that showed the strongly adsorbed form was not formed on close-packed surfaces. 

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