KINETIC-BEHAVIOR OF AN ARTIFICIALLY ROUGHENED IR(100) SURFACE

The temperature-dependent kinetic behavior of an artificially roughene d Ir(100) surface was studied by low-energy ion-scattering spectroscop y (LEIS or ISS) at temperatures in the range 110-1000 K. The surface w as created at 110 K by either thermal evaporation of Ir atoms at submo nolayer coverage on a (5 x 1)- reconstructed Ir(100) surface, or by io n bombardment of a clean (5 x 1) surface. Even at similar to 120 K, an initial smoothening of the rough surface can occur by rearrangements of scattered adatoms and neighboring vacancies. Above similar to 460 K rearrangements of atoms in the step edge region of surface patches tr ansforms their (1 x 1) structure to (5 x 1). Thus the surface is mixed with (5 x 1) and (Ix 1) structures. The fraction of (5 x 1) area incr eases along the width of the edges of roughened steps of surface patch es on prolonged annealing at a temperature above similar to 460 K Abov e 860 K the surface structure rapidly transforms into the (5 x 1) stru cture; the structural transformation is no longer kinetically limited.