Adsorption of hydrogen on clean and potassium modified low index copper surfaces: Cu(100) and Cu(110)

The adsorption of atomic hydrogen has been studied on clean and potassium m odified Cu(110) and Cu(100) surfaces. Two hydrogen induced states in the va lence band have been found on the clean Cu(110) surface, an a state recedin g in the subsurface and a beta state in the surface of the crystal. Upon an nealing, hydrogen in the subsurface both diffuses to the surface and desorb s at 330 K, and diffuses into the bulk. Two states, alpha (K) and beta (K), have also been observed on the potassium modified surfaces, with the aK st ate assigned to a potassium-hydrogen bond and the alpha (K) state assigned to a Cu-hydrogen bond. The Cu(110) surface is significantly more reactive t han the Cu(100) surface. (C) 2001 American Vacuum Society.