No abstract

No abstract

No abstract

The electronic structure and the geometric arrangement of picene molecules adsorbed on Ag(111) were studied by means of photoemission and near-edge X-ray absorption fine-structure spectroscopies (NEXAFS). While the valence band of a picene monolayer shows a clear metallic state that evolves with alkali metal doping, in the case of a picene multilayer there is no evidence of metallic states evolving with doping. Our data suggest that the bulk ultrahigh-vacuum films of K x picene are in an insulating phase, and we attribute this behavior to a strong electron–electron Coulomb interaction that is instead screened in the monolayer. The NEXAFS profiles of different picene layers show a coverage-dependent orientation, from flat molecules (monolayer) to an orientation of ∼40° of the molecular long axis with respect to the substrate surface (multilayer). The observed molecular orientations are in disagreement with the expected crystal structure of the bulk material and may explain the presence of insulating states in strongly correlated doped picene multilayers.

Available online xxxKeywords: Hydrogen storage Graphene oxide Interlayer space Functional group Reduce graphene oxide Structural characterization a b s t r a c t Hydrogen storage properties of the derivatives of graphene, graphene oxide/reducedgraphene oxide are studied in this paper. Modified Hummer's method was adopted for synthesis of graphene oxide (GO) and reduced-graphene oxide (rGO). The morphology of GO/rGO was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The presence of C]O and eOH group in the Fourier transform infrared (FTIR) spectrum and G-mode and 2D-mode in the micro-Raman studies confirmed the synthesis of the GO and rGO. Furthermore, the structural investigations using powder x-ray diffraction (XRD) reveals the hexagonal crystallographic phase of GO/rGO. The hydrogenstorage capacity of the GO/rGO sample is measured using indigenously fabricated high pressure hydrogen storage Sieverts' type volumetric setup at room temperature and pressure up to 80 bars. In present experimental investigations, GO was found to exhibit better H 2 uptake capacity (1.90wt.%) as compared to rGO (1.34 wt.%) at room temperature. It can be said that the oxygen functional groups work as spacers in between the graphene layers and increase the inter-layer space which in turn accumulate more number of hydrogen molecules on surface of carbon nano-sheets.

A number of 1N-substituted-2-methyl benzimidazole derivatives have been synthesized and tested for their antibacterial activities. The chemical structures of the newly synthesized compounds were verified on the basis of spectral and elemental methods of analyses. Investigation of antimicrobial activity of the compounds was done by disc diffusion method using Gram-positive (S. aureus, S. mutans and B. subtilis), Gram-negative (E. coli, S. typhi and P. aeruginosa) bacteria and fungi (C. albicans, A. flavus and A. niger). Among the compounds tested 5a, 5b, 5d, 5i, 5j and 5k exhibited good antibacterial activities against Gram positive bacteria, while 5d and 5i also showed notable antifungal activity. Specially compounds 5a and 5b exhibited appreciable activity against S. aureus and B. subtilis comparable to reference drugs.

No abstract

Growth conditions, structural, and optical properties of MgO nanostructure have been investigated. Surface composition and shift in binding energy of Mg at 50.8 eV due to oxidation were examined by core-level spectroscopy. The SEM showed that the film is dense, and grain growth and crystallinity are enhanced by post-deposition annealing. Grain distribution was appraised within the confinement of 24.51 μm 2 from the selected scan areas. X-ray diffraction studies indicated prominent peaks, which are attributed to (111), (200), and (220) reflections from fairly crystallized and randomly oriented MgO thin film. Plane (111) is found to be the preferred orientation of the film. The film transmitted well across the visible spectrum and the estimated energy band gap is 5.41 eV. Absence of catalyst in the electrolyte solution aided the purity of the sample.