Domain-wall interactions in Bi/Cu(001)

Surface X-ray diffraction has been used to determine the two-dimensional structures of Bi adsorbed on Cu(100) at coverages of 0.56 and 0.60 monolayers. At the lower coverage, a c(9 root 2 x root 2)R45 domain wall structure is formed consisting of a uniaxial dislocation array with a single row of Bi atoms inserted per unit cell. The p(10 x 10) structure at 0.6-monolayer coverage is a two-dimensional array of similar dislocations. This system presents a unique opportunity to observe the structure of the vertex formed when two dislocations cross and interact with each other. The mechanism of the interaction is revealed by analyzing the individual displacements of the atoms from their ideal lattice sites in both structures. (C) 1998 Elsevier Science B.V. All rights reserved.