Domain-wall interactions in Bi/Cu(001)

Surface X-ray diffraction has been used to determine the two-dimensional st ructures 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 cov erage is a two-dimensional array of similar dislocations. This system prese nts 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 at oms from their ideal lattice sites in both structures. (C) 1998 Elsevier Sc ience B.V. All rights reserved.