Direct observation of the removal of the ‘‘missing row’’ reconstruction of the clean Pt(110) surface under the influence of CO adsorption by scanning tunneling microscopy revealed that at 300 K this process is initiated by homogeneous nucleation of small characteristic 1×1 patches. Their further growth is limited by thermal activation; migration of Pt atoms is restricted to a few lattice sites. At higher temperatures, correlated jumps cause the lateral displacement of longer chains, and the enhanced surface mobility leads to the formation of larger, strongly anisotropic 1×1 islands.

• Received 26 May 1989

DOI:https://doi.org/10.1103/PhysRevLett.63.1086