Selective Transition of Chemisorbed Hydrogen to Subsurface Sites on Pd(110)

Conclusive evidence is provided for the first time that through adsorbate-induced surface-structure changes, effective channels open for hydrogen to move from the surface to the interior of metals. In Pd(110), all available subsurface sites between the first and the second metal layers can be selectively populated by thermal activation from a specific type of chemisorption place, which is associated with a substrate reconstruction at high hydrogen surface coverage.