Hydrogen-induced subsurface reconstruction of Cu(110)

Room-temperature adsorption of atomic hydrogen on Cu(110) initially yields a (1×2)* phase visible with low-energy electron diffraction but not with atom diffraction; this surprising observation suggests that H moves below the surface and induces a reconstruction in deeper layers. Upon further H uptake the (1×2) periodicity extends to the surface and also becomes visible with atom diffraction. Low-temperature phases, in which H adsorbs above the surface, transform at 240 K into the (1×2) reconstructed phases, proving that H subsurface movement requires thermal activation. © 1986 The American Physical Society.