Direct Imaging of Reconstructed Iridium Surfaces in the Field Ion Microscope

Experiments are described during which both the Ir(llO)lx2 and the Ir(1OO)lxS reconstructed surfaces could be imaged in the FIM. Furthermore evidence for a possible 1x2 reconstruction of the Ir(113) surface was found. Introduction It is well khown that on many semiconductor and some metal surfaces the topmost layer of atoms can rearrange to form structures different from those of the underlying bulk net planes. These reconstructed surfaces have been studied mainly by diffraction and scattering techniques. Except for two studies /1, 2/ FIM has contributed rather little to this subject up to now. With its unique capability of imaging single surface atoms, however, it should be able to reveal valuable atomic details of the reconstruction process inaccessible to other techniques. In the following a short account of experiments will be given during which both the reconstructed Ir(llO)lx2 and the Ir(100)1x5 surfaces as well as their emergence from the respective 1x1 structures were observed in the FIM. The experiments are described in more detail elsewhere / 3 / .