Atomic structures and atomic steps in the reconstruction of Ir (001), (110) and (131) surfaces, induced by nanosecond-pulsed-laser heating, were observed in the field-ion microscope. The quasi-hexagonal arrangement of atoms in a (1 x 5)-reconstructed Ir (001) plane was revealed for the first time by mapping the position of surface atoms in a reconstructed layer while it was gradually field evaporated. Thus even though field-ion images of these surfaces were consistent with models proposed from studies using low-energy electron diffraction and other macroscopic techniques, there were a few significant differences in the detailed atomic arrangements. The Ir (110) surface reconstructed from the (1 x 1) to the (1 x 2) structure by breaking of [110] atomic rows into fragments of two to several atoms and by lateral and cross-channel jumps of these fragments. The simultaneous jump of small rows of atoms was probably induced by surface soliton waves. The (131) surface of Ir also tended to reconstruct from the (1 x 1) to the (1 x 2) structure. The (1 x 2) structure which was observed for Ir (110) and (131) surfaces was consistent with the so-called simple missing-row model.

Direct Observation of Atomic Structures in the Surface Reconstruction of Ir and Pt (001), (110), and (131) Surfaces. Q.J.Gao, T.T.Tsong: Physical Review B, 1987, 36, 2547-56