BaFe 2 As 2 exhibits properties characteristic of the parent compounds of the newly discovered iron (Fe)-based high-T C superconductors. By combining the real space imaging of scanning tun-neling microscopy/spectroscopy (STM/S) with momentum space quantitative Low Energy Electron Diffraction (LEED) we have identified the surface plane of cleaved BaFe 2 As 2 crystals as the As terminated Fe-As layer-the plane where superconductivity occurs. LEED and STM/S data on the BaFe 2 As 2 (001) surface indicate an ordered arsenic (As)-terminated metallic surface without reconstruction or lattice distortion. It is surprising that the STM images the different Fe-As orbitals associated with the orthorhombic structure, not the As atoms in the surface plane.

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Electronic structure of nickel nanoparticles encapsulated in carbon was characterized by photoelectron, X-ray absorption, and X-ray emission spectroscopies. Experimental spectra are compared with the density of states calculated in the frame of the density functional theory.The carbon shell of Ni nanoparticles has been found to be multilayer graphene with significant (about 6%) amount of Stone-Wales defects. Results of the experiments evidence protection of the metallic nanoparticles from the environmental degradation by providing a barrier against oxidation at least for two years. Exposure in air for 2 years leads to oxidation only of the carbon shell of Ni@C nanoparticles with coverage of functional groups.

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Keywords: N,O ligands / Cubanes / Magnetic properties / X-ray absorption spectroscopy / X-ray photoelectron spectroscopyUnder anaerobic conditions, the reactions of cobalt(II) and nickel(II) acetate tetrahydrate with 2,6-pyridinedimethanol (H 2 L 2 , 3) in anhydrous acetonitrile afforded two tetranuclear metal(II) complexes [M II 4 (HL 2 ) 4 (OAc) 4 ] (4; M II = Co 2+ , Ni 2+ ) with a [M 4 (μ 3 -O) 4 ] 4+ cubane core. X-ray structural analyses revealed that both M II cubanes 4a·2CH 3 OH and 4b·2CH 3 OH are isostructural and crystallize in the tetragonal space group I4 1 /acd with eight molecules in the unit cell. In the solid state, the orientation of the cubane cores of 4 and the formation of a 3D framework were controlled by π-π interactions as well as intra-and intermolecular O-H···O hydrogen bonds.