Surface umklapp effects and surface states on Ir(100)-(1×1), Ir(100)-(5×1) and Ir(111)

The (1×1)→(5×1) reconstruction of the Ir(100) surface has been observed to introduce final state surface umklapp scattering which significantly affects intensities of bulk interband transitions as well as secondary electron features observed in angle-resolved photoemission spectra. In particular, a strongly directional bulk interband transition observed in normal emission from the Ir(100)-(1×1) surface is found to be much weaker for the (5×1) reconstructed surface due to surface umklapp scattering. Previously, this emission feature had been attributed to surface state emission from Ir(100)-(1×1). For Ir(111)-(1×1) we find a Λ1 symmetry surface state at 0.4 eV below the Fermi level at the zone center Γ. © 1980.