Bi ordered phases on Cu(100): Periodic arrays of dislocations influence the electronic properties

A single layer of bismuth deposited on the Cu(100) surface forms long range ordered structural phases at various Bi density. A highly ordered c(2 x 2) reconstruction is accomplished at 0.5 ML, further Bi deposition induces a c(9 root 2 x root 2)R45 degrees structure and a subsequent p(10 x 10) phase related to the formation of regular dislocations arrays. The transition from a c(2 x 2) superstructure to the c(9 root 2 x root 2)R45 degrees phase is accompanied by a sudden decrease in the work function. Photoemission measurements reveal that the Bi induced states close to the Fermi level, associated to the c(2 x 2) phase, are strongly quenched when the arrays of dislocations are formed, while at higher binding energies, they undergo an energy shift probably due to a confinement effect. The low-energy single particle excitations and the electron dispersion of the Bi induced states of the c(2 x 2) phase are compared to the electronic states deduced by theoretical band structure obtained by ab initio calculation performed within the embedding method applied to a realistic semi-infinite system.