CN-induced surface layer expansion of Ni(110): a MEIS study

Medium energy ion scattering (MEIS) using 100 keV H+ incident ions has been used to determine the outermost substrate layer spacings of clean Ni(1 1 0) and Ni(1 1 0)c(2×2)-CN. Experimental blocking curves were obtained using [100], [112] and [101] ion incident directions and these have been interpreted with the aid of theoretical simulations for different model structures. For the Ni(1 1 0)c(2×2)-CN surface phase the ion scattering data indicate a substrate outermost layer expansion of 21.2±1.6%, providing independent confirmation of the large CN-induced surface layer relaxation obtained in an earlier scanned-energy mode photoelectron diffraction study of this surface.