Photoemission electron microscopy of arrays of submicron nickel rods in a silicon dioxide matrix

Arrays of Ni rods ($\sim$500 nm diameter) formed by the ion-track technology in combination with electrochemical deposition into a SiO$_2$ matrix on the surface of single-crystal silicon plates have been investigated using photoemission electron microscopy with high-intensity synchrotron (undulator) radiation. An analysis of the Ni $L_{2,3}$ X-ray absorption near-edge structure (XANES) spectra has demonstrated that rod-like structures in pores and connecting bridges between the rods are formed by a metallic nickel phase, which is stable to oxidation by atmospheric oxygen. No formation of intermediate compound phases (nickel silicides and oxides) is observed at the Ni/SiO$_2$ heterojunction, whereas oxidized nickel(II) species are identified on the surface of the SiO$_2$ matrix, which presumably can be attributed to nickel silicate and hydroxide compounds formed upon nickel(II) chemisorption in electrochemical deposition electrolytes.