Template Synthesis and Optical Properties of Small Metal Particle Composite Materials: Effects of Particle Shape and Orientation On Plasmon Resonance Maxima.

1992 ◽  
Vol 286 ◽  
Author(s):  
Colby A. Foss ◽  
Gabor L. Hornyak ◽  
Jon A. Stockert ◽  
Charles R. Martin
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Electrochemical Method ◽  
Metal Particle ◽  
Particle Composite ◽  
Gold Particles ◽  
Near Ir ◽  
Surface Enhanced ◽  
Uv Visible ◽  
Small Metal Particle

ABSTRACTAn electrochemical method for the preparation of nanoscopic gold particles which allows for the control of particle size, shape and orientation is described. The UV/visible/near-IR spectra of Au/alumina and Au/polyethylene composites are described and shown to be in accord with the predictions of Maxwell-Garnett theory. The applications of such composites to surface enhanced spectroscopy are also discussed.

scholarly journals Effect of Reduction Atmosphere on Structure and Catalytic Performance of PtIn/Mg(Al)O/ZnO for Propane Dehydrogenation

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 485
Author(s):  
Ming Zhang ◽  
Zhen Song ◽  
Mengquan Guo ◽  
Xiangxiang Li ◽  
Yanjun Lin ◽  
...  
Keyword(s):  
Particle Size ◽  
Metal Particle ◽  
Catalytic Performance ◽  
Coke Deposition ◽  
Molar Ratio ◽  
Propane Conversion ◽  
Characterization Methods ◽  
Metal Particle Size ◽  
The Stability ◽  
Small Metal Particle

The effect of reduction atmospheres, H2/N2, C3H8/H2/N2, C3H8 and CO, on the structure and propane direct dehydrogenation performance of PtIn/Mg(Al)O/ZnO catalyst derived from ZnO-supported PtIn-hydrotalcite was studied. The physicochemical properties of the as-prepared and used catalytic system were characterized by various characterization methods. The results show that the dehydrogenation performance, especially the stability of the PtIn/Mg(Al)O/ZnO catalyst, was significantly improved along with the change in reduction atmosphere. The highest catalytic activity (51% of propane conversion and 97% propylene selectivity), resistance toward coke deposition, and stability for more than 30 h were achieved with the H2/N2-reduced catalyst. The optimal dehydrogenation performance and coke resistance are mainly related to the high Pt dispersion and In0/In3+ molar ratio, strong Pt–In interaction and small metal particle size, depending on the nature of the reduction atmospheres. The reconstruction of meixnerite favors the stability and coke resistance to some extent.

Optical properties of nanosized gold particles

1996 ◽  
Vol 11 (11) ◽  
pp. 2834-2840 ◽  
Author(s):  
Robert H. Doremus ◽  
Pratima Rao
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Absorption Spectrum ◽  
Absorption Band ◽  
Small Particle ◽  
Small Particle Size ◽  
Free Electrons ◽  
Gold Particles ◽  
Plasma Absorption ◽  
Good Agreement

Gold particles smaller than 2 nm in diameter were grown in glass. Their optical absorption spectrum did not show the usual plasma absorption band for gold particles; this band was spread by the small particle size. The absorption spectrum was calculated from the bulk optical properties of gold, modified for the small particle size; there was good agreement between calculated and measured spectra. The smallest particles containing from 20 to 40 gold atoms showed a λ−4 dependence of absorption on wavelength λ. This result implies that the absorption in these particles was entirely from free electrons at wavelengths above 0.3 μm.

Surface enhanced two photon absorption near a small metal particle

1988 ◽  
Vol 89 (10) ◽  
pp. 6497-6505 ◽  
Author(s):  
Purna C. Das ◽  
Horia Metiu ◽  
Ashok Puri
Keyword(s):  
Metal Particle ◽  
Photon Absorption ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Surface Enhanced ◽  
Small Metal Particle

scholarly journals Self-assembled graphene-based microfibers with eclectic optical properties

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mahdi Ghamsari ◽  
Tayyebeh Madrakian ◽  
Abbas Afkhami ◽  
Mazaher Ahmadi
Keyword(s):  
Optical Properties ◽  
Free Standing ◽  
Mechanical And Electrical Properties ◽  
Near Ir ◽  
The Subject ◽  
Uv Visible ◽  
Self Assembled ◽  
Optical Applications ◽  
Upconversion Emissions ◽  
Tunable Interference

AbstractThe construction of graphene-based microfibers with reinforced mechanical and electrical properties has been the subject of numerous researches in recent years. However, the fabrication of graphene-based fibers with remarkable optical features still remains a challenge and has not been addressed so far. This paper aims to report a series of flexible self-assembled fibers, synthesized through a few-minute sonication of thermally oxidized graphene oxide nanosheets, so-called Nanoporous Over-Oxidized Graphene (NOG), in an acidic medium. These free-standing glassy fibers were classified into four distinct morphological structures and displayed a collection of intriguing optical properties comprising high transparency, strong birefringence, fixed body colorations (e.g. colorless, blue, green, and red), tunable interference marginal colorations, UV–visible-near IR fluorescence, and upconversion emissions. Moreover, they exhibited high chemical stability in strongly acidic, basic, and oxidizing media. The foregoing notable attributes introduce the NOG fiber as a promising candidate both for the construction of graphene-based photoluminescent textiles and the development of a wide variety of optical applications.

Size Effect on Optical Properties of Silicon Dioxide Hollow Particles

2020 ◽  
Vol 312 ◽  
pp. 26-31
Author(s):  
Viktoriia Iurina ◽  
Vitaly V. Neshchimenko ◽  
Chun Dong Li
Keyword(s):  
Optical Properties ◽  
Silicon Dioxide ◽  
Near Infrared ◽  
Photoelectron Spectra ◽  
Hollow Particles ◽  
X Ray ◽  
Near Ir ◽  
Infrared Spectral ◽  
Uv Visible ◽  
Spectral Ranges

The optical properties of silicon dioxide hollow particles with different size were investigated in UV/visible/near-IR region, as well as X-ray photoelectron spectra were analyzed. Synthesis of SiO2 hollow particles was carried out using a template method. It was established that hollow particle reflectance lower than bulk microparticles. Absorptance in the red and near infrared spectral ranges increases with decreasing size of hollow particles, but in the UV-region conversely. This is due to different absorption centers.

Electron Microscopy of the Shape of Small Metal Particles

1977 ◽  
Vol 35 ◽  
pp. 300-301
Author(s):  
M. Jose Yacaman
Keyword(s):  
Electron Microscopy ◽  
Metal Particle ◽  
Field Experiments ◽  
Size Range ◽  
Dark Field ◽  
Metal Particles ◽  
Bragg Condition ◽  
Crystal Particle ◽  
Small Metal Particle ◽  
Small Metal Particles

In the Study of small metal particles the shape is a very Important parameter. Using electron microscopy Ino and Owaga(l) have studied the shape of twinned particles of gold. In that work electron diffraction and contrast (dark field) experiments were used to produce models of a crystal particle. In this work we report a method which can give direct information about the shape of an small metal particle in the amstrong- size range with high resolution. The diffraction pattern of a sample containing small metal particles contains in general several systematic and non- systematic reflections and a two-beam condition can not be used in practice. However a N-beam condition produces a reduced extinction distance. On the other hand if a beam is out of the bragg condition the effective extinction distance is even more reduced.

scholarly journals Polymer Composites with 0.98 Transparencies and Small Optical Energy Band Gap Using a Promising Green Methodology: Structural and Optical Properties

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1648
Author(s):  
Muaffaq M. Nofal ◽  
Shujahadeen B. Aziz ◽  
Jihad M. Hadi ◽  
Wrya O. Karim ◽  
Elham M. A. Dannoun ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Polymer Composites ◽  
Amorphous Phase ◽  
Absorption Edge ◽  
Complex Form ◽  
Bandgap Energy ◽  
Optical Parameters ◽  
Visible Spectroscopy ◽  
Uv Visible

In this work, a green approach was implemented to prepare polymer composites using polyvinyl alcohol polymer and the extract of black tea leaves (polyphenols) in a complex form with Co2+ ions. A range of techniques was used to characterize the Co2+ complex and polymer composite, such as Ultraviolet–visible (UV-Visible) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The optical parameters of absorption edge, refractive index (n), dielectric properties including real and imaginary parts (εr, and εi) were also investigated. The FRIR and XRD spectra were used to examine the compatibility between the PVA polymer and Co2+-polyphenol complex. The extent of interaction was evidenced from the shifts and change in the intensity of the peaks. The relatively wide amorphous phase in PVA polymer increased upon insertion of the Co2+-polyphenol complex. The amorphous character of the Co2+ complex was emphasized with the appearance of a hump in the XRD pattern. From UV-Visible spectroscopy, the optical properties, such as absorption edge, refractive index (n), (εr), (εi), and bandgap energy (Eg) of parent PVA and composite films were specified. The Eg of PVA was lowered from 5.8 to 1.82 eV upon addition of 45 mL of Co2+-polyphenol complex. The N/m* was calculated from the optical dielectric function. Ultimately, various types of electronic transitions within the polymer composites were specified using Tauc’s method. The direct bandgap (DBG) treatment of polymer composites with a developed amorphous phase is fundamental for commercialization in optoelectronic devices.

scholarly journals Green Light Emission ofZnxCd1-xSeNanocrystals Synthesized by One-Pot Method

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Shu-Ru Chung ◽  
Kuan-Wen Wang ◽  
Hong-Shuo Chen
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Light Emission ◽  
Green Light ◽  
Particle Size Effect ◽  
Partial Replacement ◽  
Face Centered Cubic ◽  
One Pot ◽  
Zn Content ◽  
High Emission

We present a facile one-pot synthesis to prepare ternaryZnxCd1-xSe(x= 0.2, 0.5, 0.8, and 1) nanocrystals (NCs) with high emission quantum yield (QY, 45~89%). The effect of Zn content (x) ofZnxCd1-xSeNCs on their physical properties is investigated. The NCs have a particle size of 3.2 nm and face centered cubic structure. However, the actual compositions of the NCs are Zn0.03Cd0.97Se, Zn0.11Cd0.89Se, and Zn0.38Cd0.62Se when Zn content is 0.2, 0.5, and 0.8, respectively. In terms of the optical properties, the emission wavelength shifts from 512 to 545 nm with increasing Zn content from 0 to 0.8 while the QY changes from 89 to 45, respectively. Partial replacement of Cd by Zn is beneficial to improve the QY of Zn0.2and Zn0.5NCs. The optical properties of ternary NCs are affected by compositional effect rather than particle size effect.

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