LEED STUDY OF ACTIVATED NITROGEN ADSORPTION ON (100) AND (H11) FACES OF COPPER

LEED observations on nitrogen adsorbed on (h11) stepped and (100) copp er faces have shown the existence of two surface phases with a first o rder transition. The first one corresponds, on the (100) face, to the formation of an ordered stepped overlayer composed of alternating squa re c(2 x 2)N island and bare copper of [100] atomic rows and on the (h 11) stepped faces, to an unusual nitrogen induced faceting into (100) and (h'11) facets: the terrace width of these (h'11) facets decreases with coverages and a (h11) stepped face (h = 65 +/- 4) with large (100 ) terrace widths is observed. The second phase, in the ultimate state of adsorption might correspond to the formation of a copper nitride su rface layer in epitaxy on all the copper faces under investigation.