Interaction of hydrogen with solid surfaces

The present article focusses on the chemosorptive and physisorptive behavior of hydrogen interacting with solid surfaces. Depending on the electronic structure of the solid hydrogen will either physically interact and form a weak van der Waals type of bond, or the H2 molecule will dissociate and the H atoms will form a chemical bond with the surface atoms. In some cases the interaction is not just restricted to the surface but may lead to absorption or even hydride formation. Also, reversible or irreversible changes of the structure of the solid may occur as the hydrogen is interacting. This leads to relaxation, reconstruction and facetting phenomena. After some introductory remarks recent results on H2 physisorption and H chemisorption phenomena will be presented and compiled whereby emphasis is put on metal single crystal work. Particular attention will be paid to the energetics and kinetics of the adsorption process, and to the structural properties of hydrogen adsorbed layers. In this context, order-disorder transitions within chemisorbed phases will be considered as well as structural phase transformations involving the underlying solid surfaces (H-induced surface reconstruction). Thereafter a section will be devoted to theoretical model calculations describing the mechanisms of the H chemisorption and the bonding.