Dynamic observations of nanoscale self-assembly on solid surfaces

Using low-energy electron microscopy, we find that Cu and Pb, arranged in single atomic layers on the Cu(111) surface, self-assemble into ordered, nanoscale domain patterns. The pattern type, feature size, and degree of long-range order vary controllably with surface composition and temperature. The continuous evolution of the domain structures from circular islands to stripes to `inverted' islands with increasing Pb coverage agrees with theoretical predictions and simulations based on the existence of competing long- and short-range interactions. The details of the self-assembly process depend on a number of factors including temperature, surface morphology, and the presence of small amounts of sulfur.