The phonon dispersion method was used to investigate the dynamics of the (1 x 1) → (5 x 1) reconstruction of an Ir(100) surface. The Ir(100) surface was chosen here mainly because stable and atomically clean surfaces of both unreconstructed Ir(100)-(1 x 1) and reconstructed Ir(100)-(5 x 1) could be routinely obtained by controlling experimental conditions. The results indicated that the frequency of the Rayleigh phonon near to the zone boundary was significantly higher on the unreconstructed (1 x 1) surface. In addition, lattice dynamic calculations in a second-nearest neighbour force constant model were also performed for the unreconstructed Ir(100)-(1 x 1) surface. The comparison of theory with experimental results reveals that the unreconstructed surface possesses a substantial amount of tensile surface stress. The results presented here permitted it to be conclude that the surface stress was the major driving force for the surface reconstruction of Ir(100)-(1 x 1) to Ir(100)-(5 x 1).

A Surface Stress Induced (1 x 1) → (5 x 1) Reconstruction of an Ir(100) Surface. J.G.Chen, S.Lehwald, G.Kisters, E.Preuss, H.Ibach: Journal of Electron Spectroscopy and Related Phenomena, 1990, 54-55, 405-13