In the electrodeposition of metals, a widely used industrial technique, bubbles of gas generated near the cathode can adversely affect the quality of the metal coating. Here we use phase-contrast radiology with synchrotron radiation to witness directly and in real time the accumulation of zinc on hydrogen bubbles. This process explains the origin of the bubble-shaped defects that are common in electrodeposited coatings.

Tests performed in different regimes reveal the interplay of two edge-enhancement mechanisms in radiological images taken with coherent synchrotron light. The relative weight of the two mechanisms, related to refraction and to Fresnel edge diffraction, can be changed in a controlled way. This makes it possible to obtain different images of the same object with complementary information.

Chemical mechanical polishing (CMP) is considered as the paradigm shift that enabled optical photolithography to continue down to 0.12 m. Currently, the polishing physics is not well defined though it is known that the nature of the process makes particle removal after CMP difficult and necessary. It is important to understand the particle adhesion mechanisms resulting from the polishing process and the effect of the adhering force on particle removal in post-CMP cleaning processes. In this paper, strong particle adhesion is shown to be caused by chemical reactions (after initial hydrogen bonding) that take place in the presence of moisture and long aging time. In particle removal using brush cleaning, contact between the particle and the brush is essential to the removal of submicron particles. In noncontact mode, 0.1-m particle can hardly be removed when the brush is more than 1 maway from the particle. While in full contact mode, removal is possible for a 0.1-m particle at the investigated brush rotational speeds. The experimental data shows that high removal efficiency (low number of defects) is possible with a high brush pressure and a short cleaning time.

An attempt to explain the origin of the vivid red color in precious pink and red corals was undertaken. Raman and IR spectroscopies were applied to characterize white, pink and red corals. The position of the Raman signal near 1500 cm −1 of some corals and pearls was associated by several authors with the presence of the mixture of all-trans-polyenic pigments, containing 6-16 conjugated C C bonds or β-carotenoids. This hypothesis was examined theoretically by performing extensive B3LYP-DFT calculations of vibrational spectra of the model polyenic compounds. The B3LYP/6-311++G * * predicted positions of the dominating Raman mode depend on the number of C C units (Cn parameter) and can be accurately predicted for larger systems from a simple nonlinear fit. The DFT-predicted Raman activities of these modes are extremely sensitive to Cn, and sharply increase with the number of double bonds. This implies a presence of only -two to three polyenes differing slightly in the number of C C units as the source of color in pink and red corals.

SummaryThe main goal of this work is to study the structural and magnetic properties of iron nanowires and iron nanoparticles, which have been fabricated in almost the same processes. The only difference in the synthesis is an application of an external magnetic field in order to form the iron nanowires. Both nanomaterials have been examined by means of transmission electron microscopy, energy dispersive X-ray spectrometry, X-ray diffractometry and Mössbauer spectrometry to determine their structures. Structural investigations confirm that obtained iron nanowires as well as nanoparticles reveal core–shell structures and they are composed of crystalline iron cores that are covered by amorphous or highly defected phases of iron and iron oxides. Magnetic properties have been measured using a vibrating sample magnetometer. The obtained values of coercivity, remanent magnetization, saturation magnetization as well as Curie temperature differ for both studied nanostructures. Higher values of magnetizations are observed for iron nanowires. At the same time, coercivity and Curie temperature are higher for iron nanoparticles.

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GaN nanowire and Ga 2 O 3 nanowire and nanoribbon growth from ion implanted iron catalystGa ϩ ion implantation of chemical-vapor-deposited GaN nanowires ͑NWs͒ is studied using a 50-keV Ga ϩ focused ion beam. The role of dynamic annealing ͑defect-annihilation͒ is discussed with an emphasis on the fluence-dependent defect structure. Unlike heavy-ion-irradiated epitaxial GaN film, large-scale amorphization is suppressed until a very high fluence of 2ϫ10 16 ions cm Ϫ2 . In contrast to extended-defects as reported for heavy-ion-irradiated epitaxial GaN film, point-defect clusters are identified as major component in irradiated NWs. Enhanced dynamic annealing induced by high diffusivity of mobile point-defects in the confined geometry of NWs is identified as the probable reason for observed differences.

The Pd-Au multiwall carbon nanotubes (MWCNTs) supported catalyst exhibits higher power density in direct formic acid fuel cell (DFAFC) than similar Pd/MWCNTs catalyst. The Pd-Au/ MWCNTs catalyst also exhibits higher activity and is more stable in electrooxidation reaction of formic acid during cyclic voltammetry (CV) measurements. After preparation by polyol method, the catalyst was subjected to two type of treatments: (I) annealing at 250 8C in 100% of Ar, (II) reducing in 5% of H 2 in Ar atmosphere at 200 8C. It was observed that the catalyst after treatment I was completely inactive, whereas after treatment II exhibited high activity.In order to explain this effect the catalysts were characterized by electron spectroscopy methods. The higher initial catalytic activity of Pd-Au/MWCNTs catalyst than Pd/MWCNTs catalyst in reaction of formic acid electrooxidation was attributed to electronic effect of gold in Pd-Au solution, and larger content of small Au nanoparticles of 1 nm size. The catalytic inactivity of Pd-Au/MWCNTs catalysts annealed in argon is attributed to carbon amorphous overlayer covering of Pd oxide shell on the metallic nanoparticles.