PREPARATION OF IR(100)-1X1 SURFACE-STRUCTURES BY SURFACE-REACTIONS AND ITS RECONSTRUCTION KINETICS AS DETERMINED WITH LEED, UPS AND WORK FUNCTION MEASUREMENTS

A procedure is described which allows routine preparation of clean unreconstructed 1 × 1 surface structures of Ir(100) single crystal surfaces. Evidence is given that those unreconstructed surfaces are not stabilized by detectable amounts of impurities. From UPS it is suggested that upon reconstruction a reorganisation within the Ir d-bands take place. By comparison with photo-emission from a Ir(111) surface there is strong evidence that the hexagonal overlayer model is a correct description of the reconstructed 5 × 1 surface. A 1 × 1 surface structure transforms to the well known 5 × 1 structure with temperature-dependent kinetics, the 1 × 1 structure being stable below ≈800 K. An analysis of the reconstruction kinetics leads to an apparent activation energy of 20 kcal{plus 45 degree rule}mole for the 1 × 1-5 × 1 structure conversion. A determination of the oxygen sticking coefficient on both surface structures demonstrate marked chemical differences between those surfaces. © 1979.