OBSERVATION OF SUPERSTRUCTURE PERIODICITY IN ANGLE-RESOLVED PHOTOEMISSION FROM CU(610)

Angle-resolved ultra-violet photoemission measurements are reported fr om Cu(610). a surface that consists of (100) terraces regularly separa ted by steps running along [001]. A surface state, analogous to the (M ) over bar Tamm state on Cu(100), is found to be present. The energy p osition of this state is displaced similar to 40 meV away from E-F com pared to the related Tamm state. This energy shift is determined by th e degree of inter-step confinement. The momentum of the Cu(610) surfac e state is given by the projection of the X point of the bulk band str ucture onto the surface Brillouin zone, and its periodicity reflects t hat of the steps. A possible observation of back folding of the surfac e state band due to the step super-structure is also observed. (C) 199 8 Elsevier Science B.V. All rights reserved.