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Stable electroactive mixed films of osmium oxide/hexachloroplatinate, osmium oxide and platinum have been deposited on different electrode materials by cycling the electrode potential repetitively in solution containing Os3+ and PtCl. The film growth of was monitored by using cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). The cyclic voltammetric features of modified electrode in Os3+ solution resembles that of surface wave, and involves ions-exchange with Os3+ ions present in the solution. Based on the SEM results the modifier was considered as one-dimensional, mixed-valent polymeric film, and stabilized by Os3+/2+ counter ions. Finally, the electrocatalytic activity of the modified electrode was examined toward reduction of NAD+, chloroacetic acids and nitrous oxide.

Particles of osmium or an inorganic polymeric film of osmium oxide-ruthenium cyanide (OsO-RuCN) electrodeposited on glassy carbon (GC) electrocatalyze the oxidation of dopamine (DA), adrenaline (AD), and noradrenaline (NAD). It is found that these biogenic amines are determined with a high sensitivity by oxidation at an electrode with an OsO-RuCN film. Procedures for the voltammetric determination of DA, AD, or NAD at a composite film electrode are developed. The currents of the substrate oxidation are linear functions of the concentrations in the ranges from 5 × 10−7 to 1 × 10−3 M for DA and from 1 × 10−6 to 1 × 10−3 M for AD and NAD.

Osmium oxide/hexacyanoruthenate films have been prepared using repeated cyclic voltammetry, and their electrocatalytic properties have been investigated. The osmium oxide/hexacyanoruthenate films were deposited directly from mixed Os3+ and Ru ( CN ) 6 4 - ions in a pH 2 solution. Electrochemical quartz crystal microbalance (EQCM), cyclic voltammetry, and UV–visible spectroscopy were used to study the growth mechanism of the osmium oxide/hexacyanoruthenate films. The EQCM data indicated that the redox process was confined to the immobilized osmium oxide/hexacyanoruthenate film, which showed a single redox couple with a formal proton-dependent potential at 0.35 V. The electrocatalytic oxidation of dopamine, epinephrine, and norepinephrine and S 2 O 3 2 - and SO 5 2 - by the osmium oxide/hexacyanoruthenate films was studied. The electrocatalytic reactions of the osmium oxide/hexacyanoruthenate films were also investigated by the rotating ring-disk electrode method.

In the present work, the morphology and composition of osmium deposits formed in submonolayer amount on Pt(1 0 0) and Pt(1 1 1) single crystal surfaces either by spontaneous deposition or by electrolysis at 50 mV in different deposition times ( t dep ), were studied. The cyclic voltammetric curves for Pt(1 0 0)/Os and Pt(1 1 1)/Os were recorded in the potential range where the oxidation of deposited osmium species occurs, which suggests that the chemical composition of the deposits is a mixture of metallic Os and OsO 2 . The ratio of each species deposited depends directly on the deposition potential, as well as the surface structure characteristics. The composition of the modified platinum single crystal surfaces has also been estimated by X-ray photoelectron spectroscopy (XPS), whose results agree with those obtained by CV, about the amount of osmium oxide on Pt(1 1 1) to be higher than on Pt(1 0 0). This feature of the Pt(1 1 1)/Os becomes its surface more active for ethanol oxidation at lower potentials than that observed for Pt(1 0 0)/Os, although at high potentials the high presence of OsO 2 is prejudicial to the catalytic activity of the electrode. The Pt–Os surfaces were also explored by use of the scanning tunneling microscopy (STM) technique in order to image the features of osmium deposits on platinum, after a short and a long deposition time. It was found, by using spontaneous deposition procedure, that the dimensions of osmium deposits islands do not grow with the increase of degree of coverage of osmium on the surface, as well as they keep the monoatomic thickness.

A new, rapid, low-blank method for extraction of osmium from geological materials is described. As with existing techniques, this new Os accumulation procedure relies upon the oxidation of Os in the sample solution to OsO 4 and utilises the volatile nature of this oxide. In contrast to previous distillation methods, however, osmium oxide is caught in a cold trap, coated on its inner surface with sulfuric acid instead of bubbling an Os oxide bearing carrier gas through chilled HCl or HBr. Once the distillation is complete, the trapped Os is extracted into 500 μl of HBr concentration and undergoes a final cleaning step which can be accomplished by employing conventional micro-distillation techniques. The entire extraction procedure from the sample solution takes approximately 90 min and requires only 2 μl of H 2 SO 4 to trap the osmium, which is achieved with great efficiency. Thus, apart from the digestion medium, the extraction and recovery of Os in this technique employs a total of only ∼502 μl of reagents instead of approximately 5–10 ml in conventional procedures that ‘see’ the Os. As demonstrated here, the efficient extraction of Os and low reagent volumes required mean that it is possible to achieve yields of 80% and total procedural blanks of 100 fg routinely.

Phase structures of binary and ternary blends of polycarbonate (PC) with poly(styrene-co-acrylonitrile) (PSAN), and poly(methyl methacrylate-co-styrene) (PMMAS) were examined by transmission (TEM) and/or scanning transmission electron microscopy (STEM). Osmium or ruthenium tetroxides were applied to ultrathin sections and significant differences in the staining of phases were observed: PC was stained most intensely, while staining of the PSAN- and PMMAS-rich phases was affected by the concentration of the dissolved (partially miscible) PC. The blends within the phase inversion interval contained both PC continuous and PC dispersed phases, which were observed at different places on the sample cross-section. Three-phase structure, found in ultrathin sections of binary blends and confirmed on plasma-etched cut surfaces, is discussed from the point of view of likely artefacts; a possible interpretation considers non-uniform blending in the melt.

Pressure dependence of superconducting transition temperature $T_{\rm c}$ has been determined through the DC magnetic measurements under pressure up to $P$=10 GPa for $\beta$-pyrochlore oxides AOs$_2$O$_6$ with A=Cs ($T_{\rm c}$=3.3 K), Rb (6.3 K) and K (9.6 K). Both for A=Rb and Cs, $T_{\rm c}$ increases with increasing $P$ and shows a saturation at $T_{\rm cm}$$\sim$8.8 K, which is considered as the upper limit of $T_{\rm c}$ inherent in AOs$_2$O$_6$. In contrast, the $T_{\rm c}-P$ curve for KOs$_2$O$_6$ shows a sharp maximum of $\sim$10 K at $P$$\sim$0.5 GPa, and $T_{\rm c}$ is higher than $T_{\rm cm}$ for 0$\leq$$P$$\leq$1.5GPa, suggesting the enhanced superconductivity due to the rattling of K ions., Comment: 4 pages, 4 figures, to be published in J. Phys. Soc. Jpn. Vol. 77, No. 4 (2008)

Single-walled carbon nanotubes have been reacted with osmium tetroxide (OsO(4)) in solution in the presence of O(2) and UV irradiation at 254 nm. We observe one main structural motif, namely thickly coated nanotube structures, densely covered with OsO(2), consisting of multiple bundles of derivatized tubes. In a few instances, bridging uncoated tubes, connecting these thickly coated structures, incorporate a number of smaller nanotube bundles, projecting out from the larger functionalized aggregates of tubes. It is believed that OsO(2) (a) initially forms on the nanotubes by the preferential covalent sidewall functionalization of metallic nanotubes and (b) subsequently self-aggregates. The formation of an intermediate charge-transfer complex is likely the basis for the observed selectivity and reactivity of metallic tubes. Extensive characterization of these osmylated adducts has been performed using a variety of electron microscopy and optical spectroscopy techniques.

The periodic table provides a classification of the chemical properties of the elements. But for the heaviest elements, the transactinides, this role of the periodic table reaches its limits because increasingly strong relativistic effects on the valence electron shells can induce deviations from known trends in chemical properties. In the case of the first two transactinides, elements 104 and 105, relativistic effects do indeed influence their chemical properties, whereas elements 106 and 107 both behave as expected from their position within the periodic table. Here we report the chemical separation and characterization of only seven detected atoms of element 108 (hassium, Hs), which were generated as isotopes (269)Hs (refs 8, 9) and (270)Hs (ref. 10) in the fusion reaction between (26)Mg and (248)Cm. The hassium atoms are immediately oxidized to a highly volatile oxide, presumably HsO(4), for which we determine an enthalpy of adsorption on our detector surface that is comparable to the adsorption enthalpy determined under identical conditions for the osmium oxide OsO(4). These results provide evidence that the chemical properties of hassium and its lighter homologue osmium are similar, thus confirming that hassium exhibits properties as expected from its position in group 8 of the periodic table.

Magnetic and lattice properties of the pyrochlore NaxOs2O6?H2O were studied by a synchrotron X-ray diffraction method, measurements of magnetic susceptibility, electrical resistivity, and specific heat. The results indicated little change in the properties over the Na range 0.5 ? x ? 1.4. Any trace of superconductivity was undetected to 2 K.

The emission spectrum of OsO has been photographed in the region 405–875 nm where many new bands have been observed. In favorable cases the 190 OsO 192 OsO isotopic splittings have been resolved and aid in vibrational assignments. Three visible bands in the region 433–470 nm have been assigned as (1,0), (0,0), and (0,1) of a ΔΩ = 0 electronic transition. The (0,0) and (0,1) bands have been rotationally analyzed, yielding principal constants (cm−1) for the visible system of ν0 = 22 273.3, B′0 = 0.3657, D′0 = 2.8 × 10−7, B″e = 0.4023, D″e = 3.2 × 10−7, Δ G″( 1 2 ) = 780.7 , and Δ G″( 1 2 ) = 884.9 . A band at 825.4 nm has been found to be a ΔΩ = +1 (0,0) band with the same lower state as in the analyzed visible bands. Constants for the upper state of the ir system are ν0 = 12 109.7, B′0 = 0.3845, and D′0 = 3.1 × 10−7 cm−1.

The emerald green solid, OsOF5, m. p. 59·2, b. p. 100·6°, is the major product of the fluorination of osmium dioxide. Vapour pressure–temperature relationships for the compound are: 32–59°(solid), log Pmm=–2266//T+ 9·064; 59–105°(liquid), log Pmm=–1911//T+ 7·994. The solid is dimorphic being orthorhombic below the transition point of 32·5° and body centred cubic, a= 6·14 A, above it. It is paramagnetic and the susceptibility obeys the Curie-Weiss law approximately, with θ=+6°, the temperature independent magnetic moment being, µ= 1·47 B.M. The infrared spectrum of OsOF5(gas) is similar to that of ReOF5(gas) and is consistent with C4v molecular symmetry.