The electronic structure of thin Co nanoislands on Cu(111) has been investigated below and above the Fermi level (E(F)) by scanning tunneling spectroscopy at low temperature. Two surface related electronic states are found: a strong localized peak 0.31 eV below E(F) and a mainly unoccupied dispersive state, giving rise to quantum interference patterns of standing electron waves on the Co surface. Ab initio calculations reveal that the electronic states are spin polarized, originating from d3(z(2)-r(2))-minority and sp-majority bands, respectively.

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A synthesis route to rock-salt zinc oxide (rs-ZnO), high-pressure phase metastable at ambient conditions, has been developed. High-purity bulk nanocrystalline rs-ZnO has been synthesized from wurtzite (w) ZnO nanopowders at 7.7 GPa and 770-820 K and for the first time recovered at normal conditions. Structure, phase composition and thermal phase stability of recovered rs-ZnO have been studied by synchrotron X-ray powder diffraction and X-ray absorption spectroscopy (XANES and EXAFS) at ambient pressure. Phase purity of rs-ZnO was achieved by usage of w-ZnO nanoparticles with narrow size distribution as a pristine material synthesized by various chemical methods. At ambient pressure rs-ZnO could be stable up to 360 K. The optical properties of rs-ZnO have been studied by conventional cathodoluminescence in high vacuum at room and liquid-nitrogen temperatures. The nanocrystalline rs-ZnO at 300 and 77 K has shown bright blue luminescence at 2.42 and 2.56 eV, respectively. KEYWORDS cubic zinc oxide, nanocrystals, high-pressure synthesis, phase transition, luminescent properties.