scholarly journals Infrared study of nonstoichiometric anatase TiO2 nanopowders

2006 ◽  
Vol 38 (2) ◽  
pp. 183-189 ◽  
Author(s):  
M. Grujic-Brojcin ◽  
M. Scepanovic ◽  
Z. Dohcevic-Mitrovic ◽  
Z.V. Popovic
Keyword(s):  
Small Deviation ◽  
Anatase Phase ◽  
Plasmon Mode ◽  
Charge Carriers ◽  
Spectroscopy Analysis ◽  
Infrared Study ◽  
Reflectivity Spectrum ◽  
Deviation From Stoichiometry ◽  
Tio2 Nanopowders ◽  
Good Agreement

The infrared (IR) reflectivity of laser synthesized TiO2 nanopowder in the anatase phase with a small deviation from stoichiometry is reported. The samples were characterized by SEM, XRD and BET measurements as well as Raman and photoluminescence spectroscopy. Analysis of the far IR reflectivity spectrum of the nanopowder reveals a presence of a plasmon mode. The charge carriers resulting from the lattice defects, mainly oxygen vacancies, are responsible for this mode. The dielectric function in a factorized form with a plasmon contribution is used to model the IR reflectivity spectrum and a good agreement between theoretical and experimental results has been found.

Enhanced-Fluorescence of a Dye on DNA- assembled Gold Nano-Dimers Discriminated by Lifetime Correlation Spectroscopy

2017 ◽  
Author(s):  
Pedro M. R. Paulo ◽  
David Botequim ◽  
Agnieszka Jóskowiak ◽  
Sofia Martins ◽  
Duarte M. F. Prazeres ◽  
...  
Keyword(s):  
Single Molecule ◽  
Fluorescence Emission ◽  
Directed Assembly ◽  
Plasmon Mode ◽  
Correlation Spectroscopy ◽  
Enhanced Fluorescence ◽  
Detection Volume ◽  
Relaxation Component ◽  
Good Agreement ◽  
Confocal Detection

<div> <div> <div> <p>We have employed DNA-directed assembly to prepare dimers of gold nanoparticles and used their longitudinally coupled plasmon mode to enhance the fluorescence emission of an organic red-emitting dye, Atto-655. The plasmon- enhanced fluorescence of this dye using dimers of 80 nm particles was measured at single molecule detection level. The top enhancement factors were above 1000-fold in 71% of the dimers within a total of 32 dimers measured, and, in some cases, they reached almost 4000-fold, in good agreement with model simulations. Additionally, fluorescence lifetime correlation analysis enabled the separation of enhanced from non-enhanced emission simultaneously collected in our confocal detection volume. This approach allowed us to recover a short relaxation component exclusive to enhanced emission that is attributed to the interaction of the dye with DNA in the interparticle gaps. </p> </div> </div> </div>

A Fourier Transform Infrared Study of Mineral Matter in Coal: The Application of a Least Squares Curve-Fitting Program

1981 ◽  
Vol 35 (1) ◽  
pp. 102-106 ◽  
Author(s):  
Paul C. Painter ◽  
Susan M. Rimmer ◽  
Randy W. Snyder ◽  
Alan Davis
Keyword(s):  
Fourier Transform ◽  
Least Squares ◽  
Curve Fitting ◽  
Fourier Transform Infrared ◽  
Mineral Matter ◽  
Infrared Study ◽  
Least Squares Curve Fitting ◽  
Mineral Mixtures ◽  
Good Agreement

The application of Fourier transform infrared spectroscopy to the quantitative determination of mineral matter in coal is discussed. The use of a least squares curve-fitting program allows a choice between standards to be made. The results of an analysis of mineral mixtures and a coal low temperature ash are presented. The results are in good agreement with known concentrations and those obtained by other methods of analysis.

Optical band-gap of TiO2 nanopowders doped with Al2O3

2013 ◽  
Vol 1493 ◽  
pp. 281-286
Author(s):  
Keisuke Yoshimura ◽  
Tetsuya Hashimoto ◽  
Hiroshi Katsumata
Keyword(s):  
Band Gap ◽  
Ball Mill ◽  
Milling Time ◽  
Optical Band Gap ◽  
The Other ◽  
Mass Ratio ◽  
Quantum Size ◽  
Powder Mass ◽  
Tio2 Nanopowders ◽  
Good Agreement

ABSTRACTOptical band-gap and cathode luminescence (CL) properties of anatase TiO2 nanopowders mixed with γ- Al2O3 powders by planetary ball mill were evaluated as a function of a powder mass ratio (x=Al2O3/TiO2) of 0 to 0.5 and their correlation with XRD spectra was also investigated. The optical band-gap of TiO2 increased from 3.36 eV to 3.41eV with increasing milling time (tm) up to 600 min, which was in good agreement with the blue shifts observed in the CL spectra with increasing tm and it was interpreted as a quantum size effect. In addition, the optical band-gap of TiO2 powders mixed with Al2O3 with tm=60min greatly increased from 3.36 eV to 3.48 eV with increasing x up to x=0.5. On the other hand, the optical band-gap of all the powders was decreased by annealing at temperatures above 600°C, which was evidenced by the XRD spectra to be due to the growth of grain size.

Plasmon spectrum of graphene monolayer on substrate

2019 ◽  
Vol 33 (09) ◽  
pp. 1950102
Author(s):  
I. N. Askerzade ◽  
R. T. Askerbeyli
Keyword(s):  
Substrate Material ◽  
Plasmon Mode ◽  
Monolayer Graphene ◽  
Graphene Monolayer ◽  
Multilayer Graphene ◽  
Linear Dispersion ◽  
Long Wavelength ◽  
Theoretical Considerations ◽  
Plasmon Spectrum ◽  
Good Agreement

Plasmon modes in monolayer graphene on substrate are analyzed taking into account the thickness of graphene and substrate material layer in the evaluation of Coulomb potential. It is shown that plasmon mode in graphene monolayer has linear dispersion in contrast to multilayer graphene in long-wavelength limit. The slope of plasmon spectrum is determined by the thickness and dielectric constant of substrate. Obtained results are in good agreement with experimental data and other theoretical considerations.

scholarly journals Electrochemical Study of Anodized Titanium in Phosphoric Acid

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
M. Khadiri ◽  
M. Elyaagoubi ◽  
R. Idouhli ◽  
Y. Koumya ◽  
O. Zakir ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Charge Carriers ◽  
Flat Band ◽  
X Ray Diffraction ◽  
X Ray ◽  
Type Semiconductor ◽  
Anodized Titanium ◽  
Spectroscopy Studies ◽  
Schottky Model ◽  
Good Agreement

The anodization of the Ti-Cu (2%) alloy was carried out in a 5M H3PO4 solution for 2 minutes. The obtained layers are characterized by XPS, X-ray diffraction, and Raman spectroscopy. The results showed that the obtained films are composed of poorly crystallized TiO2 oxide. Electrochemical Impedance spectroscopy studies revealed that the thickness of the formed film increases with increasing anodization potential. Additionally, the resistance of charge transfer becomes higher when the anodization potential increases. Thus, the Mott Schottky model revealed that the formed film is an n-type semiconductor. The density of charge carriers is in good agreement with those found in the literature. Also, it is found that the flat-band potential increases with increasing treatment potential.

Prediction of Fracture Appearance Transition Temperature of 2.25Cr-1Mo Steel Used in Hot-Wall Hydrofining Reactors

2005 ◽  
Vol 128 (4) ◽  
pp. 566-571 ◽  
Author(s):  
Jinzhu Tan ◽  
Wenlong Huang ◽  
Y. J. Chao
Keyword(s):  
Transition Temperature ◽  
Test Data ◽  
Electron Spectroscopy ◽  
Temper Embrittlement ◽  
Spectroscopy Analysis ◽  
Auger Electron Spectroscopy Analysis ◽  
Fracture Appearance Transition Temperature ◽  
Fracture Appearance ◽  
Predicted Values ◽  
Good Agreement

A kinetics model for temper embrittlement was employed as the basis for predicting the fracture appearance transition temperature (FATT) of 2.25Cr-1Mo steel used for hot-wall hydrofining reactors. Various heat treatments were performed to obtain different degrees of temper embrittlement for the steel. Charpy V-notch impact tests and Auger electron spectroscopy analysis were performed on embrittled 2.25Cr-1Mo steels to establish the relation between the shift of FATT and the change in the concentration of phosphorus segregated in the grain boundary of the steel. Based on the model and test data, a method of predicting the FATT at service time t was developed for the 2.25Cr-1Mo steel. Good agreement is obtained when the predicted values are compared to test data from open literature.

Electron diffraction patterns from scroll nanotubes: interpretation peculiarities

2015 ◽  
Vol 48 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Zufar Khalitov ◽  
Azat Khadiev ◽  
Dmitry Pashin
Keyword(s):  
Electron Diffraction ◽  
Small Deviation ◽  
Structure Identification ◽  
Tube Axis ◽  
Azimuthal Dependence ◽  
Characteristic Sign ◽  
Special Values ◽  
Diffraction Patterns ◽  
Diffraction Effects ◽  
Good Agreement

This article describes the structure of scroll nanotubes and associated diffraction effects in the context of electron diffraction from a single nanotube. It is suggested that the effect of multiple equidistant splitting of diffuse reflections into cone series be used as a diffraction criterion for conical scroll structure identification. For cylindrical scroll structure determination, the effect of the azimuthal dependence of the intensity of basal diffraction spots is proposed as a characteristic sign. Good agreement between specific oscillations in both theoretical and experimental profiles of basal diffraction spots was achieved. It was also established that there are special values of chiral angles in cylindrical scroll nanotubes that lead to order enhancement in their structure along the tube axis, whereas even a small deviation from these angles results in degradation of diffraction conditions for some diffraction spots in the diffraction pattern.

Eigen function and corresponding eigen values of charge carriers in V-grooves quantum wires with variable width

2016 ◽  
Vol 30 (17) ◽  
pp. 1650103
Author(s):  
Ali Hossein Mohammad Zaheri
Keyword(s):  
Effective Potential ◽  
Quantum Wire ◽  
Quantum Wires ◽  
Wave Functions ◽  
Charge Carriers ◽  
Energy Spectra ◽  
Eigen Value ◽  
Eigen Values ◽  
Interface Geometry ◽  
Good Agreement

In this work, we have calculated analytically the energy spectra of electrons and holes in V-grooves quantum wires. To modify wire structure, we have used the equations which suggested in the work of Inoshita et al. We introduce a new effective potential scheme which is applicable and matchable with actual interface geometry of this groove of ridge quantum wires. By applying this effective potential and considering a suitable transformed coordinate that allows the decoupling of the two-dimensional wave functions, we have calculated eigen values of the charge carriers in three states as well as the wave functions. We found that by increasing the curvature at the top of quantum wire [Formula: see text] the energy eigen value decreases. Our results are in good agreement with the earlier investigations.

scholarly journals Influence of some sol-gel synthesis parameters of mesoporous TiO2 on photocatalytic degradation of pollutants

2016 ◽  
Vol 22 (1) ◽  
pp. 65-73
Author(s):  
Aleksandar Golubovic ◽  
Ivana Veljkovic ◽  
Maja Scepanovic ◽  
Mirjana Grujic-Brojcin ◽  
Natasa Tomic ◽  
...  
Keyword(s):  
Anatase Phase ◽  
Sol Gel ◽  
Tetrabutyl Titanate ◽  
Textile Dye ◽  
Reactive Orange 16 ◽  
Higher Temperature ◽  
Tio2 Nanopowders ◽  
Gel Technique ◽  
Reactive Orange ◽  
Sol Gel Synthesis

The titanium dioxide (TiO2) nanopowders were produced by sol-gel technique from tetrabutyl titanate as a precursor by varying some parameters of the sol-gel synthesis like the temperature (500 and 550 ?C) and the duration of the calcination (1.5, 2, and 2.5 h). X-ray powder diffraction (XRPD) results have shown that all synthesized nanopowders are dominantly in anatase phase, with the presence of a small amount of rutile in samples calcined at 550 ?C. According to the results obtained by Williamson-Hall method, the anatase crystallite size was increased with the duration of the calcination (from 24 to 29 nm in samples calcined at lower, and from 30 to 35 nm in samples calcined at higher temperature). The analysis of the shift and linewidth of the most intensive anatase Eg Raman mode confirmed the XRPD results. The analysis of pore structure from nitrogen sorption experimental data described all samples as mesoporous, with mean pore diameters in the range of 5-8 nm. Nanopowder properties have been related to the photocatalytic activity, tested in degradation of the textile dye (C.I. Reactive Orange 16), carbofuran and phenol.

Enhanced-Fluorescence of a Dye on DNA- assembled Gold Nano-Dimers Discriminated by Lifetime Correlation Spectroscopy

2017 ◽  
Author(s):  
Pedro M. R. Paulo ◽  
David Botequim ◽  
Agnieszka Jóskowiak ◽  
Sofia Martins ◽  
Duarte M. F. Prazeres ◽  
...  
Keyword(s):  
Single Molecule ◽  
Fluorescence Emission ◽  
Directed Assembly ◽  
Plasmon Mode ◽  
Correlation Spectroscopy ◽  
Enhanced Fluorescence ◽  
Detection Volume ◽  
Relaxation Component ◽  
Good Agreement ◽  
Confocal Detection

<div> <div> <div> <p>We have employed DNA-directed assembly to prepare dimers of gold nanoparticles and used their longitudinally coupled plasmon mode to enhance the fluorescence emission of an organic red-emitting dye, Atto-655. The plasmon- enhanced fluorescence of this dye using dimers of 80 nm particles was measured at single molecule detection level. The top enhancement factors were above 1000-fold in 71% of the dimers within a total of 32 dimers measured, and, in some cases, they reached almost 4000-fold, in good agreement with model simulations. Additionally, fluorescence lifetime correlation analysis enabled the separation of enhanced from non-enhanced emission simultaneously collected in our confocal detection volume. This approach allowed us to recover a short relaxation component exclusive to enhanced emission that is attributed to the interaction of the dye with DNA in the interparticle gaps. </p> </div> </div> </div>

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