Loading...
Search for:
mie-theory
0.006 seconds
Investigation of Effective Microstructural Parameters on the Stress Whitening in Polypropylene Blends
, Ph.D. Dissertation Sharif University of Technology ; Bagheri, Reza (Supervisor)
Abstract
Stress whitening is a type of discoloration that can occur in variety of polymers used in automotive and household industries. The current research tries to investigate the effective microstructural parameters such as strain rate, rubber second phase, and branched polypropylene (PP) on the stress whitening in polypropylene in order to propose toughed PP blends with limited stress whitening. It is shown that increasing the strain rate in tensile test results in formation of more visible whitened area within the plastically deformed zone. This is the consequence of further growth of micro-voids at higher strain rates. The results are in accordance with the Mie scattering concepts. Besides, the...
CO gas sensor properties of Cu@CuO core-shell nanoparticles based on localized surface plasmon resonance
, Article Journal of Physical Chemistry C ; Volume 115, Issue 45 , 2011 , Pages 22126-22130 ; 19327447 (ISSN) ; Zahrabi, H ; Saani, M. H ; Vesaghi, M. A ; Sharif University of Technology
2011
Abstract
Hexagonal array of Cu@CuO core-shell nanoparticles (NPs) on the a-C:H thin film was prepared by codeposition of RF-sputtering and RF-PECVD. The trace of hexagonal NPs supperlattice was recognized by AFM image and XRD result. On the basis of localized surface plasmon resonance (LSPR) of core-shell NPs, the prepared array detected a low flow rate of CO gas at room temperature. XPS results indicate that the surface of Cu@CuO core-shell NPs have no chemical reaction with CO molecule. The physical absorption of CO molecule on the surface of Cu@CuO core-shell NPs increases the LSPR absorbance and causes a red shift in LSPR wavelength. These experimental results are in agreement with Mie theory...
Localized surface plasmon resonance of Cu@Cu2O coreshell nanoparticles: Absorption, scattering and luminescence
, Article Physica B: Condensed Matter ; Volume 406, Issue 13 , July , 2011 , Pages 2678-2683 ; 09214526 (ISSN) ; Vesaghi, M. A ; Sharif University of Technology
2011
Abstract
By co-deposition via RF-Sputtering and RF-PECVD methods and using Cu target and acetylene gas, we prepared Cu@Cu2O coreshell nanoparticles on the a-C:H thin film at room temperature. Mie absorption of Cu cores, scattering from Cu2O shell and luminescence that rises from carrier transfer in Cu@Cu2O interface were employed to fit the whole range of visible extinction spectrum of these coreshells. From simulation it was found that scattering and luminescence have an important effect on the energy, width and shape of LSPR absorption peak. Shift of LSPR peak is more affected by the dielectric coefficient of shell than Cu core size particularly for Cu core diameter above 4 nm. Also, the LSPR...
Study of surface plasmon resonance of Cu@Cu2O core-shell nanoparticles by Mie theory
, Article Journal of Physics D: Applied Physics ; Volume 42, Issue 1 , 2009 ; 00223727 (ISSN) ; Vesaghi, M. A ; Shafiekhani, A ; Sharif University of Technology
2009
Abstract
Cu@Cu2O core-shell nanoparticles on a-C : H thin films are prepared by co-deposition of RF-sputtering and RF-PECVD. Samples with different copper concentrations are grown. The copper content of films increases with reduction in initial pressure and rises with increasing RF power. When the Cu/C ratio reaches 0.5, the surface plasmon resonance (SPR) peak that is a signature of the formation of Cu nanoparticles appears in visible spectra of these films. X-ray photoelectron spectroscopy (XPS) characterization indicates that the surface of the copper nanoparticles oxidizes when they are exposed to air. The results are indicative that the shell of the nanoparticle is mainly the Cu 2O phase that is...
Optical and electrical properties of the copper-carbon nanocomposites
, Article Nanophotonics II, Strasbourg, 7 April 2008 through 9 April 2008 ; Volume 6988 , 2008 ; 0277786X (ISSN); 9780819471864 (ISBN) ; Vesaghi, M. A ; Shafiekhani, A ; Ahmadi, M ; Sharif University of Technology
2008
Abstract
We prepared copper-carbon nanocomposite films by co-deposition of RF-Sputtering and RF-PECVD methods at room temperature. These films contain different copper concentration and different size of copper nanoparticles. The copper content of these films was obtained from Rutherford Back Scattering (RBS) analyze. We studied electrical resistivity of samples versus copper content. A metal-nonmetal transition was observed by decreasing of copper content in these films. The electrical conductivity of dielectric and metallic samples was explained by tunneling and percolation models respectively. In the percolation threshold conduction results from two mechanisms: percolation and tunneling. In the...