Optical absorption of Cu2O in the near infrared and the role of metallic inclusions

1980 ◽  
Vol 58 (3) ◽  
pp. 325-333 ◽  
Author(s):  
F. L. Weichman ◽  
J. M. Reyes
Keyword(s):  
Experimental Data ◽  
Optical Absorption ◽  
Scattering Theory ◽  
Room Temperature ◽  
Near Infrared ◽  
Copper Films ◽  
Nonspherical Particles ◽  
Metallic Inclusions ◽  
Absorption Characteristics

We have measured the optical absorption characteristics of copper oxide single crystals in the range from 1.1 to 2.0 eV. The crystals were annealed at various oxygen pressures at high temperatures and quenched to room temperature. A major, broad, previously unknown absorption peak was found at 1.6 eV which we relate to the formation of copper inclusions in the oxide. Although experimental data on thin copper films agree with our assumptions, we cannot reconcile our results with scattering theory of small metal spheres embedded in a dielectric. Agreement between scattering theory and optical absorption may be achieved for nonspherical particles for which as yet no other experimental evidence exists.

Picosecond molecular relaxations: the role of the fluid in electron solvation

1977 ◽  
Vol 55 (11) ◽  
pp. 2009-2016 ◽  
Author(s):  
G. A. Kenney-Wallace
Keyword(s):  
Experimental Data ◽  
Room Temperature ◽  
Fluid Layer ◽  
Liquid Structure ◽  
Polar Fluid ◽  
Electron Solvation ◽  
Orientational Polarization ◽  
Excess Electrons ◽  
Electron Migration

The role of the fluid is considered for a model of electron solvation in liquid alcohols. The events that lead to trapping and solvation of excess electrons are reconstructed from experimental data on the time and frequency-dependent electron absorptions (kmol) and the appropriate molecular rotational relaxations (τ2, τc), local liquid structure, viscosity (η), and orientational polarization (β) of the supporting fluid. The quasifree electron is captured at subpicosecond times in a preexisting trap in the liquid, which in alcohols is identified as an alcohol cluster whose local configurational fluctuations will be frozen in on this timescale. Rapid configurational relaxation of the cluster molecules, including multi-phonon processes, then occurs in the field of the excess electron at times ≤10−12 s. Finally, the molecules in the fluid layer adjacent to the initial trapping site align in the now screened field of the localized electron in a manner comparable to solvation of an ion embedded in a polar fluid. The relaxation may occur in competition with electron migration and reaction. The observed rate constant of the final step kmol is shown to be proportional to βη−1 for a range of alcohols at room temperature. The implications of this model for photobleaching experiments in liquids are briefly discussed.

Near-Infrared Diode Laser Based Spectroscopic Detection of Ammonia: A Comparative Study of Photoacoustic and Direct Optical Absorption Methods

2002 ◽  
Vol 56 (6) ◽  
pp. 715-719 ◽  
Author(s):  
Zoltán Bozóki ◽  
Árpád Mohácsi ◽  
Gábor Szabó ◽  
Zsolt Bor ◽  
Miklós Erdélyi ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Room Temperature ◽  
Near Infrared ◽  
Continuous Wave ◽  
Fast Response ◽  
Minimum Detectable Concentration ◽  
Mode Of Operation ◽  
Detectable Concentration ◽  
Ammonia Detection ◽  
Ppm Level

A photoacoustic spectroscopic (PAS) and a direct optical absorption spectroscopic (OAS) gas sensor, both using continuous-wave room-temperature diode lasers operating at 1531.8 nm, were compared on the basis of ammonia detection. Excellent linear correlation between the detector signals of the two systems was found. Although the physical properties and the mode of operation of both sensors were significantly different, their performances were found to be remarkably similar, with a sub-ppm level minimum detectable concentration of ammonia and a fast response time in the range of a few minutes.

scholarly journals Role of Sawdust in the Removal of Iron from Aqueous Solution

2017 ◽  
Vol 23 (3) ◽  
pp. 223 ◽  
Author(s):  
H.B. Senin ◽  
O. Subhi ◽  
R. Rosliza ◽  
N. Kancono ◽  
M.S. Azhar ◽  
...  
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Langmuir Isotherm ◽  
Room Temperature ◽  
Freundlich Isotherm ◽  
Batch Test ◽  
Freundlich Isotherms ◽  
Langmuir And Freundlich Isotherms ◽  
Better Than

Sawdust, inexpensive material has been utilized as an absorbent for the removal of iron from aqueous solution for their safe disposal. The adsorption experiments of untreated sawdust (SD) and treated sawdust (SDC) have been carried out at room temperature using the batch test. The Langmuir and Freundlich isotherms were used to observe sorption phenomena of sawdust in the removal of iron. The results indicate that the sawdust was capable in removing iron in aqueous solution. The results have shown that the Langmuir isotherm was found well fitted into the experimental data as compared to the Freundlich isotherm. It was found that, chemisorptions and physisorption were the prime mechanism for the process of adsorption to occur between the sawdust and iron. The results also proved that the acid sulphuric treated sawdust is much better than that of untreated sawdust as an adsorbent for iron.

Assessing the Role of Inter-Molecular Interactions in a Perylene-Based Nanowire Using First-Principles Many-Body Perturbation Theory

2019 ◽  
Author(s):  
Tianlun Huang ◽  
D. Kirk Lewis ◽  
Sahar Sharifzadeh
Keyword(s):  
Perturbation Theory ◽  
Optical Absorption ◽  
First Principles ◽  
Room Temperature ◽  
Optoelectronic Properties ◽  
High Electron ◽  
Many Body ◽  
Molecular Electronic ◽  
Many Body Perturbation Theory

<div> <div> <div> <div> <p>We present a first-principles many-body perturbation theory study of the role of inter-molecular coupling on the optoelectronic properties of a one-dimensional p-stacked nanowire composed of perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) molecules on a DNA-like backbone. We determine that strong inter-molecular electronic coupling results in large bandwidths and low carrier effective masses, suggesting a high electron mobility material. Additionally, by including the role of finite temperature phonons on optical absorption via a newly presented approach, we predict that the optical absorption spectrum at room temperature is significantly altered from room temperature due to allowed indirect transitions, while the exciton delocalization and binding energy, a measure of inter-molecular electronic interactions, remains constant. Overall, our studies indicate that strong inter-molecular coupling can dominate the optoelectronic properties of π-conjugated 1D systems even at room temperature.</p> </div> </div> </div> </div>

Assessing the Role of Inter-Molecular Interactions in a Perylene-Based Nanowire Using First-Principles Many-Body Perturbation Theory

2019 ◽  
Author(s):  
Tianlun Huang ◽  
D. Kirk Lewis ◽  
Sahar Sharifzadeh
Keyword(s):  
Perturbation Theory ◽  
Optical Absorption ◽  
First Principles ◽  
Room Temperature ◽  
Optoelectronic Properties ◽  
High Electron ◽  
Many Body ◽  
Molecular Electronic ◽  
Many Body Perturbation Theory

<div> <div> <div> <div> <p>We present a first-principles many-body perturbation theory study of the role of inter-molecular coupling on the optoelectronic properties of a one-dimensional p-stacked nanowire composed of perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) molecules on a DNA-like backbone. We determine that strong inter-molecular electronic coupling results in large bandwidths and low carrier effective masses, suggesting a high electron mobility material. Additionally, by including the role of finite temperature phonons on optical absorption via a newly presented approach, we predict that the optical absorption spectrum at room temperature is significantly altered from room temperature due to allowed indirect transitions, while the exciton delocalization and binding energy, a measure of inter-molecular electronic interactions, remains constant. Overall, our studies indicate that strong inter-molecular coupling can dominate the optoelectronic properties of π-conjugated 1D systems even at room temperature.</p> </div> </div> </div> </div>

scholarly journals Энергетический спектр и оптическое поглощение углеродных наносистем на примере изомеров N 11 и 22 фуллерена С-=SUB=-84-=/SUB=-

2020 ◽  
Vol 62 (3) ◽  
pp. 484
Author(s):  
А.И. Мурзашев
Keyword(s):  
Experimental Data ◽  
Optical Properties ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Coulomb Interaction ◽  
Energy Spectra ◽  
Optical Absorption Spectra ◽  
Electronic And Optical Properties ◽  
Comparison Of The Results

Abstract The energy spectra of isomers nos. 11 and 22 of C_84 fullerene is obtained with allowance for the intrasite Coulomb interaction. Based on the obtained spectra, the optical absorption spectra of these systems are simulated. The obtained optical absorption spectra qualitatively agree well with the available experimental data. In addition, the optical absorption spectra are also calculated on the base of the energy spectra of each of the systems calculated without considering the intrasite Coulomb interaction. The comparison of the results obtained in these different models strongly demonstrates the most important role of the Coulomb interaction in the formation of the electronic and optical properties of these systems.

Fracture Mechanisms in SiC-Whisker Reinforced Alumina

1988 ◽  
Vol 120 ◽  
Author(s):  
Christophe H. Boulanger ◽  
Yih-Cherng Chiang ◽  
Azar P. Majidi ◽  
Tsu-Wei Chou
Keyword(s):  
Experimental Data ◽  
Fracture Toughness ◽  
Room Temperature ◽  
Crack Deflection ◽  
Fracture Mechanisms ◽  
Alumina Composite ◽  
Good Agreement

AbstractThe fracture mechanisms involved in the toughening of alumina by whisker reinforcement are studied at room temperature. The fracture toughness of a hot pressed SiC-whisker/alumina composite is measured and good agreement is found between the experimental data and a model that takes into account the effects of crack deflection and whisker pullout mechanisms. From the model, it is seen that the role of whisker pullout is negligible compared to that of crack deflection.

Evidence for ordered Fe3Ni

1987 ◽  
Vol 45 ◽  
pp. 216-217
Author(s):  
K.B. Reuter ◽  
D.B. Williams ◽  
J.I. Goldstein
Keyword(s):  
Experimental Data ◽  
Martensitic Transformation ◽  
Electron Diffraction ◽  
Room Temperature ◽  
Direct Evidence ◽  
Transformation Product ◽  
Iron Meteorites ◽  
X Ray ◽  
Ni Content ◽  
Temperature Transformation

In the Fe-Ni system, although ordered FeNi and ordered Ni3Fe are experimentally well established, direct evidence for ordered Fe3Ni is unconvincing. Little experimental data for Fe3Ni exists because diffusion is sluggish at temperatures below 400°C and because alloys containing less than 29 wt% Ni undergo a martensitic transformation at room temperature. Fe-Ni phases in iron meteorites were examined in this study because iron meteorites have cooled at slow rates of about 10°C/106 years, allowing phase transformations below 400°C to occur. One low temperature transformation product, called clear taenite 2 (CT2), was of particular interest because it contains less than 30 wtZ Ni and is not martensitic. Because CT2 is only a few microns in size, the structure and Ni content were determined through electron diffraction and x-ray microanalysis. A Philips EM400T operated at 120 kV, equipped with a Tracor Northern 2000 multichannel analyzer, was used.

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