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Arman A.,Islamic Azad University at Kermanshah | Ghodselahi T.,Nano Mabna Iranian Inc. | Molamohammadi M.,Islamic Azad University at Kermanshah | Solaymani S.,Islamic Azad University at Kermanshah | And 2 more authors.
Protection of Metals and Physical Chemistry of Surfaces | Year: 2015

Cu@Ni core-shell nanoparticles on a-C:H thin film were prepared by co-deposition of RF-sputtering and RF-PECVD. Samples having different Cu nanoparticle sizes were grown and then Ni layers of different thicknesses were grown over these Cu nanoparticles. Atomic force microscopy indicated that the thin film consisted of nanoparticles 6–14 nm in size. Also, in the present work the RMS roughness and PSD spectra computed from atomic force microscopy (AFM) data were used for studying the morphology of thin films. X-ray diffraction (XRD) profiles show that the Cu nanocrystal core and Ni nanocrystal shell have formed in the film and that the surfaces of these core-shells oxidize when exposed to air. The surface plasmon resonance peak of the Cu nanoparticles can be observed at about 600 nm in a region damped by the increased thickness of the Ni layer. Absorbance in the near-IR region increased as the thickness of the Ni layer increased. The edge of strong absorption observed near the IR region varied with the thickness of the Ni layer. © 2015, Pleiades Publishing, Ltd. Source


Ghodselahi T.,Nano Mabna Iranian Inc. | Arman A.,Islamic Azad University at Kermanshah
Journal of Materials Science: Materials in Electronics | Year: 2015

Cu NPs in hydrogenated amorphous carbon (a-C:H) thin films without and with different thicknesses of Ni NPs layer were prepared by co-deposition of RF-sputtering and RF-plasma enhanced chemical vapor deposition from acetylene gas and Cu and Ni targets. The content of thin films was characterized by Rutherford back scattering spectra and X-ray diffraction. The variation of the surface morphology with Ni NPs layer thickness was investigated by atomic force microscopy. The magnetoresistance (MR) of thin films without and with different thicknesses of Ni NPs layer was measured at room temperature and low magnetic field. A negative MR was observed for Cu NPs in a-C:H thin film that is changed to positive MR when Ni NPs layer thickness reaches to 10 nm and surface morphology is varied. The interesting plateaus are observed in MR that can be related to quantum confinement effect or collective movement of particles in the soft matrix of the a-C:H thin film. © 2015, Springer Science+Business Media New York. Source


Ghodselahi T.,Nano Mabna Iranian Inc. | Ghodselahi T.,Institute for Research in Fundamental Sciences | Aghababaie N.,Institute for Research in Fundamental Sciences | Mobasheri H.,University of Tehran | And 3 more authors.
Applied Surface Science | Year: 2015

Gold nanoparticles (Au NPs) were synthesized by co-deposition of RF-sputtering and RF-PECVD from acetylene gas and Au target on the carbon nanotubes (CNTs). The CNTs were prepared by thermal chemical vapor deposition (TCVD) and Pd nanoparticles catalyst. TEM image shows that high-density and uniform distribution of Au NPs were grown on the CNTs. XRD analysis indicates that Au NPs have fcc crystal structure and CNTs have a good graphite structure. Raman spectroscopy results suggest that our sample includes double-walled CNTs. It is resulted that intensity of D-band reduces and G-band intensity raises and radial breathing mode (RBM) is changed by immobilizing of Au NPs on the CNTs. Raman results that the free electrons on the CNTs increase by immobilizing of Au NPs. Also localized surface plasmon resonance (LSPR) peak of Au NPs has red-shift and broadens when it is immobilized on the CNTs. The change in LSPR peak rises from decreasing of local electrons density on the Au NPs surface. Raman and LSPR spectroscopy suggest that there are charge transferring and chemical bonds between Au NPs and CNTs. We applied the prepared sensor chips of Au NPs@CNTs to detect DNA primer at femtomolar concentration based on the LSPR technique. © 2015 Published by Elsevier B.V. Source


Ghodselahi T.,Nano Mabna Iranian Inc. | Ghodselahi T.,Institute for Research in Fundamental Sciences | Neishaboorynejad T.,Institute for Research in Fundamental Sciences | Neishaboorynejad T.,Islamic Azad University at Tehran | And 2 more authors.
Applied Surface Science | Year: 2015

We introduce a simple method to synthesize localized surface plasmon resonance (LSPR) sensor chip of Ag NPs on the hydrogenated amorphous carbon by co-deposition of RF-Sputtering and RF-PECVD. The X-ray photoelectron spectroscopy revealed the content of Ag and C atoms. X-ray diffraction profile and atomic force microscopy indicate that the Ag NPs have fcc crystal structure and spherical shape and by increasing deposition time, particle sizes do not vary and only Ag NPs aggregation occurs, resulting in LSPR wavelength shift. Firstly, by increasing Ag NPs content, in-plan interparticles coupling is dominant and causes redshift in LSPR. At the early stage of agglomeration, out-plane coupling occurs and in-plane coupling is reduced, resulting a blueshift in the LSPR. By further increasing of Ag NPs content, agglomeration is completed on the substrate and in-plan coupling rises, resulting significant redshift in the LSPR. Results were used to implement biosensor application of chips. Detection of DNA primer at fM concentration was achieved based on breaking interparticles coupling of Ag NPs. A significant wavelength shift sensitivity of 30 nm and a short response time of 30 min were obtained, where both of these are prerequisite for biosensor applications. Source


Tlu S.,Technical University of Cluj Napoca | Stach S.,University of Silesia | Ghodselahi T.,Nano Mabna Iranian Inc. | Ghaderi A.,Islamic Azad University at Kermanshah | And 3 more authors.
Journal of Physical Chemistry B | Year: 2015

In the present work three-dimensional (3-D) surface topography of Cu-Ni nanoparticles in hydrogenated amorphous carbon (Cu-Ni NPs @ a-C:H) with constant thickness of Cu and three thicknesses of Ni prepared by RF-Plasma Enhanced Chemical Vapor Deposition (RF-PECVD) system were investigated. The thin films of Cu-Ni NPs @ a-C:H with constant thickness of Cu and three thicknesses of Ni deposited by radio frequency (RF)-sputtering and RF-PECVD systems, were characterized. To determine the mass thickness and atomic structure of the films, the Rutherford backscattering spectroscopy (RBS) spectra was applied. The absorption spectra were applied to study localized surface plasmon resonance (LSPR) peaks of Cu-Ni NPs (observed around 608 nm in visible spectra), which is widened and shifted to lower wavelengths as the thickness of Ni over layer increases, and their changes are also evaluated by the 3-D surface topography. These nanostructures were investigated over square areas of 1 μm × 1 μm using atomic force microscopy (AFM) and multifractal analysis. Topographic characterization of surface samples (in amplitude, spatial distribution, and pattern of surface characteristics) highlighted 3-D surfaces with multifractal features which can be quantitatively estimated by the multifractal measures. The 3-D surface topography Cu-Ni NPs @ a-C:H with constant thickness of Cu and three thicknesses of Ni prepared by RF-PECVD system can be characterized using the multifractal geometry in correlation with the surface statistical parameters. © 2015 American Chemical Society. Source

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