The electronic structure of orthorhombic

We present the results of an investigation, both theoretical and experimental, of partially occupied and unoccupied electronic distributions in orthorhombic . The occupied Al states near are p - d hybridized in interaction with Ru 4d states, whereas they are almost purely s-like in character beyond 6 eV from . The Ru 4d states are found close to ; their interaction with the Al states produces an important depletion of the Al 3s - d and Al 3p distributions. As a result, the Al edges are somewhat pushed back from . Thus a wide range of energy with almost no states is present in the occupied band side. lies close to the bottom of the unoccupied band where both unoccupied Al states and unoccupied Ru states are present. These results are compared to previous data for icosahedral quasicrystalline .