We report a facile electrochemical route for the one-step fabrication of ZnO nanowire (NW) arrays. The method is seed-layer-free, and the NWs are directly attached to a fluorine-doped tin oxide (FTO) substrate. The effects of growth temperature, precursor concentration, substrate etching, and deposition time on the layer morphology and structure are analyzed. The ZnO NWs are vertically well-aligned and textured with the c-axis normal to the substrate. The growth of the more vertically oriented initial wires is favored by a self-alignment process, and the layer texturing with the c-axis oriented normal to the surface is increased upon deposition. NWs with aspect ratios higher than 30 have been synthesized. The as-grown layers were superhydrophilic, and they were converted to superhydrophobic by surface derivatization with stearic acid (SA). The surface could be commuted back from superhydrophobic to superhydrophilic by a simple acetone washing. The present work demonstrates the importance of oxide NW length to control the hydrophobic state of the surface. By increasing the NW length (and then the aspect ratio), a transition between a Wenzel state and a Cassie−Baxter state was found. For long and homogeneous ZnO NWs, the hysteresis is low (5.5°), and the advancing and receding contact angles are high (168.3°/162.8° max). The role of wire density is discussed. The superhydrophobic layers are of interest for self-cleaning surfaces, biological experiments, and nano/microfluidics.

We describe a simple Zeeman slower design using permanent magnets. Contrary to common wire-wound setups no electric power and water cooling are required. In addition, the whole system can be assembled and disassembled at will. The magnetic field is however transverse to the atomic motion and an extra repumper laser is necessary. A Halbach configuration of the magnets produces a high quality magnetic field and no further adjustment is needed. After optimization of the laser parameters, the apparatus produces an intense beam of slow and cold 87 Rb atoms. With typical fluxes of 1 to 5 × 10 10 atoms/s at 30 m · s −1 , our apparatus efficiently loads a large magneto-optical trap with more than 10 10 atoms in one second, which is an ideal starting point for degenerate quantum gases experiments.