Origin of spin polarization in an edge boron doped zigzag graphene nanoribbon: a potential spin filter.

To realize a graphene based spintronic device, the prime challenge is to control the electronic structure of edges. In this work we find the origin of the spin filtering property in edge boron doped zigzag graphene nanoribbons (ZGNRs) and provide a guide to preparing a graphene based next-generation spin filter based device. Here, we unveil the role of orbitals (p-electron) to tune the electronic, magnetic and transport properties of edge B doped ZGNRs. When all the edge carbon atoms at one of the edges of ZGNRs are replaced by B (100% edge B doping), the system undergoes a semiconductor to metal transition. The role of passivation of the edge with single/double atomic hydrogen on the electronic properties and its relation with the p-electron is correlated in-depth. 50% edge B doped ZGNRs (50% of the edge C atoms at one of the edges are replaced by B) also show half-metallicity when the doped edge is left unpassivated. The half-metallic systems show 100% spin filtering efficiency for a wide range of bias voltages. Zero-bias transmission function of the other configurations shows asymmetric behavior for the up and down spin channels, thereby indicating their possible application potential in nano-spintronics.

Spectrophotometric determination of osmium with 1-phenyl-4,4,6-trimethyl-(1H,4H)-2-pyrimidinethiol and extraction into molten naphthalene.

Conditions have been developed for the spectrophotometric determination of osmium with 1-phenyl-4,4,6-trimethyl-(1H,4H)-2-pyrimidinethiol after extraction of the complex into molten naphthalene. Beer's law holds for the concentration range of 4-77 mug of osmium in 10 ml of the final solution. The molar absorptivity is 1.33 x 10(4) l.mole(-1).cm(-1). The reagent is highly selective for osmium.

Heteroepitaxial Junction in Au-ZnSe Nanostructure: Experiment versus First-Principle Simulation.

Composing together the experimental as well as the simulated results, we demonstrate here the atomic placements and the electronic structure at the epitaxial junction of a solution-processed heteronanostructure Au-ZnSe. Despite the large lattice mismatch (∼32%) between fcc Au and zinc-blende structured ZnSe, the heterostructures are formed via coincidence site epitaxy, which appears periodically because of the arrangements of their proper unit cell placements at the junction. This reduces the interface energy and drives the formation of such heteronanostructures. Details of the physical processes involved in the formation of these nanostructures have been discussed in this letter, and epitaxy at the heterojunction is strongly supported by HRTEM measurement and DFT calculation. This material has the possibility of plasmon-exciton coupling and therefore might be a futuristic material for utilizations in catalysis, nanoelectronics, and other related applications.

Manifestation of long-range ordered state in layered VX2 (X = Cl, Br, I) systems.

We report the first-principles based density functional investigation of correlated magnetic behavior for the layered VX2 (X = Cl, Br, I) system both in bulk and monolayer forms. The bulk system stabilizes in the Néel 120° spin structure with the onset of long-range order at a very low temperature. However, a monolayer of the same system results in a two-dimensional long-range ordered spin-gel configuration in the a-b plane. The occurrence of this two-dimensional non-collinear long-range order for such hexagonal systems with honeycomb topology may provide an additional feature for controlling the use of such materials in magnetic memory devices.

h-BN monolayer on the Ni(111) surface: a potential catalyst for oxidation.

The hexagonal boron nitride (h-BN) is traditionally considered to be inert. In sharp contrast to the inert behavior of free-standing hexagonal boron nitride (h-BN), we propose the catalytic property of h-BN monolayer on Ni(111) substrate using first-principles density functional theory investigation. The interaction of O2 molecule with the h-BN/Ni(111) substrate results in nondissociative adsorption of the molecule along with elongation of the O-O bond. This can be considered as the activated state of the O2 molecule. Further interaction of this complex viz O2-h-BN/Ni(111) with an incoming CO molecule leads to the spontaneous formation of CO2. Interestingly, the CO adsorption on the h-BN/Ni(111) substrate was found to be unfavorable, thereby implying the oxidation of CO selectively through Eley-Rideal (ER) mechanism.

Spectrophotometric determination of copper in environmental samples by solid-liquid extraction of its 9, 10-phenanthrenequinone monoximate complex into molten naphthalene.

A fairly selective and sensitive spectrophotometric method has been developed for determination of copper after extraction of its 9, 10-phenanthrenequinone monoximate complex into molten naphthalene in the pH range of 6.1-8.4. At room temperature, the solid naphthalene containing the metal complex is separated by filtration, dissolved in dimethylformamide (DMF) and the absorbance measured at 470 nm against the reagent blank. Beer's law is obeyed in the concentration range, 0.0-9.6 micrograms of copper in 10ml of DMF. The molar absorptivity and sensitivity are 6.30 X 10(4) 1 mol-1 cm-1 and 0.001 micrograms cm-2, respectively. The interference of various ions has been studied and the method has been applied for the determination of copper in various standard reference materials, beers, wines, human hair and environmental samples.