The Pulse Radiolysis of Dimethylsulfoxide and Binary Mixtures with Water

1973 ◽  
Vol 51 (13) ◽  
pp. 2195-2206 ◽  
Author(s):  
T. K. Cooper ◽  
D. C. Walker ◽  
H. A. Gillis ◽  
N. V. Klassen
Keyword(s):  
Dielectric Constant ◽  
Optical Properties ◽  
Absorption Band ◽  
Linear Relationship ◽  
Half Life ◽  
Pulse Radiolysis ◽  
Water Molecules ◽  
Solvated Electrons ◽  
Free Ion ◽  
Pure Dmso

The simultaneous interaction of solvated electrons with strongly solvating water molecules and weakly solvating dimethylsulfoxide (DMSO) molecules has been studied by pulse radiolysis. In all DMSO/H2O mixtures investigated the solvated electrons have a single absorption band with a maximum intermediate between that of pure DMSO (λmax > 1500 nm) and that of water (λmax = 720 nm). There is a nearly linear relationship between the photon energy of λmax and the bulk dielectric constant, indicating that the optical properties of solvated electrons in the mixtures are not dominated by the water. A minimum is observed in the variation of Gεmax with DMSO/H2O composition which may be associated with intermolecular structure. In mixtures containing > 0.2 mole fraction DMSO the solvated electrons have half-lives of 11–18 ns.The radiation produced oxidizing species in DMSO has a half-life of 1–4 µs and an absorption band centered at 600 nm. This species seems to be present in all DMSO/H2O mixtures.Pure DMSO gives a free-ion yield in the range 1.2 to 1.8, as determined separately for the oxidizing and reducing species by bromide and anthracene scavenging experiments respectively. This free-ion yield is in keeping with the dielectric constant of DMSO of 46. The yields in fully deuterated DMSO are ~30% higher than in the protonated material.

Pulse Radiolysis of Formamide and Formamide–Water Mixtures

1971 ◽  
Vol 49 (20) ◽  
pp. 3398-3401 ◽  
Author(s):  
D. C. Walker ◽  
S. C. Wallace
Keyword(s):  
Dielectric Constant ◽  
Absorption Spectrum ◽  
Absorption Band ◽  
Optical Absorption ◽  
Optical Absorption Spectrum ◽  
Pulse Radiolysis ◽  
Water Molecules ◽  
Pure Liquid ◽  
Solvated Electrons ◽  
Hydrated Electrons

From the optical absorption spectrum observed by a sub-nanosecond pulse radiolysis method it is concluded that irradiated pure liquid formamide (dielectric constant = 109) does not yield solvated electrons with lifetimes >10−11 s. In formamide–water mixtures the hydrated electron is formed in low yield and the position of the absorption band of eaq− is not altered by changing the composition. Apparently formamide reacts much more rapidly with thermalized electrons than it does with hydrated electrons. The latter may be formed in formamide–water mixtures due to aggregates of water molecules.

Yield of free-ions in the radiolysis of formamide, a liquid of very high dielectric constant

1970 ◽  
Vol 48 (11) ◽  
pp. 1657-1663 ◽  
Author(s):  
D. A. Head ◽  
D. C. Walker
Keyword(s):  
Dielectric Constant ◽  
High Dielectric Constant ◽  
Solvated Electrons ◽  
Decomposition Products ◽  
Polar Liquids ◽  
Molecular Decomposition ◽  
Total Ionization ◽  
Free Ion ◽  
High Dielectric ◽  
Very High

Solutions of N2O in liquid formamide (dielectric constant 109) gave a yield of N2 during γ-radiolysis of G(N2) = 3.3 ± 0.3. Competition between N2O and other scavengers, including water, ethanol, acids, AgNO3, and CdI2 strongly resembled the pattern of reactivity characteristic of solvated electrons found in other polar liquids. Furthermore, the yield obtained (3.3) was consistent with the high dielectric constant and predicted for the free-ion yield by Freeman's model assuming a total ionization of 4.7. However, the absence of an absorption band in nanosecond pulse radiolysis experiments suggests that solvated electrons were not present 10−9 s after the passage of the ionizing radiation. It is quite possible that in this system "solvent anions" (or other reactive reducing ions) were formed in yield equal to the "free-ion" yield. This presupposes that formamide anions readily reduce N2O and Ag+, are inactivated by H+ and do not react with water and alcohols.The high dielectric constant apparently leads to large yields of comparatively long-lived (> 10−7 s) reducing ions (free-ion yield of 3.3) accompanied by rather small yields of H atoms and simple molecular decomposition products. In these respects the radiolysis decomposition of formamide resembles that of water.

Effect of non-annealed and annealed ZnO on the optical properties of PVC/ZnO nanocomposite films

2021 ◽  
pp. 089270572110386
Author(s):  
Ali F Al-Shawabkeh ◽  
Ziad M Elimat ◽  
Khaleel N Abushgair
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Zno Nanoparticles ◽  
Oscillator Strengths ◽  
Nanocomposite Films ◽  
Optical Parameters ◽  
Zno Nanoparticle ◽  
Dispersion Energy ◽  
Optical Susceptibility

The goal of this study was to investigate the optical properties of the prepared polyvinyl chloride (PVC)/zinc oxide (ZnO) nanocomposite films. The PVC/ZnO nanocomposite films consist of the addition of different concentrations with both non-annealed ZnO nanoparticles and ZnO nanoparticles annealed at temperature of 700°C. The PVC/ZnO nanocomposite films by weight concentrations of (0 wt.%, 2.5 wt.%, 5 wt.% and 10 wt.%) have been prepared by the casting method. The optical absorbance and transmittance values of the composites films were measured in the wavelength range between (250 to 1100 nm) at room temperature by using the UV-1800 Shimadzu spectrophotometer. The optical properties (absorption coefficient, dielectric constant, refractive index, and optical conductivity) have been investigated by the ultraviolet (UV) spectrophotometer. The optical parameters (direct optical energy gap, excitation energy for electronic transitions, the dispersion energy, static refractive index, static dielectric constant, optical oscillator strengths, the moments of optical spectrum, linear optical susceptibility, third-order nonlinear optical susceptibility, nonlinear refractive index, high-frequency dielectric constant, the carrier concentration to the effective mass ratio, the long wavelength refractive index and the plasma frequency) were calculated. The results showed that the optical properties behavior of the PVC/ZnO nanocomposite films was found to be dependent on the ZnO concentration, and photon wavelength. In addition, the results of the study show that the optical parameters can be influenced by alter the concentration of the nonannealed and annealed a ZnO nanoparticle in the PVC polymer matrix.

Study the Effect of Heat Treatment and Pressure on some the Optical Properties of the Pure PVA Nano Polymer

2021 ◽  
Vol 900 ◽  
pp. 16-25
Author(s):  
Tabarak Mohammed Awad ◽  
May A.S. Mohammed
Keyword(s):  
Heat Treatment ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Polyvinyl Alcohol ◽  
Complex Dielectric Constant ◽  
Different Temperatures ◽  
German Origin ◽  
Increasing Temperature

In this study, some optical properties were studied of the pure vinyl polyvinyl alcohol (PVA) nanopolymer (German origin). Under the influence of different temperatures and pressures of PVA. Where 25 samples were prepared for the purpose of conducting the research. Which studied the study of these samples was done by recording the absorbance and transmittance spectra of the wavelengths (200-900) nm. From them, absorbance, transmittance, reflectivity, absorption coefficient, refractive index, extinction coefficient, complex dielectric constant were calculated. At different temperatures (25,40, 80, 120, 160)°C. And with different pressures within the range (7.5,8,8.5,9,9.5) MPa. The results are that the permeability of the polymer (PVA) at different temperatures for each pressure decreases with increasing temperature, and that all other calculated optical properties increase with increasing temperature.

scholarly journals Preparation and Studying the Optical Properties of (Sb2o3) Thin Films

2018 ◽  
Vol 26 (10) ◽  
pp. 249-256
Author(s):  
Waleed Khalid Kadhim
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Thermal Evaporation ◽  
Glass Slide ◽  
Antimony Trioxide ◽  
Hot Plate ◽  
Different Thickness

In this paper I present the preparation of (Sb2o3) thin films using thermal evaporation in vacuum, procedure with different thickness  (100 ,150 ,200 ,and 250) nm, by using ( hot plate) from Molybdenum matter at temperature in ( 9000c) and the period of time (15mint) ,the prepared in a manner thermal evaporation in a vacuum and precipitated on glass bases, pure Antimony Trioxide (sb2o3 ) thin films with various condition have been successfully deposited by (T.E.V) on glass slide substrates. The substrates temperature of about 100oC and the vacuum of about 10-6 torr, to investigated oxidation of evaporated, measure spectra for prepared films in arrange of wavelength (250 – 1100 nm). The following optical properties have been calculated: the absorption coefficient, the forbidden (Eg) for direct and indirect transitions "absorbance, refractive index,  extinction coefficient, real and imaginary parts" of the dielectric constant.

scholarly journals Empirical Relation for Electronic and Optical Properties of Binary Tetrahedral Semiconductors

2021 ◽  
Keyword(s):  
Dielectric Constant ◽  
Optical Properties ◽  
Atomic Number ◽  
Energy Gap ◽  
Empirical Relation ◽  
Average Energy ◽  
Optical Parameters ◽  
Dielectric Analysis ◽  
Average Atomic Number ◽  
Tetrahedral Semiconductors

The concept of ionicity has been developed by Phillips and Van Vechten from the dielectric analysis of the semiconductors and insulators to evaluate various bond parameters of binary tetrahedral (AIIBVI and AIIIBV) semiconductors. In this paper, an advance hypothesis of average atomic number of the elements in a compound has been used to evaluate intrinsic electronic and optical parameters such as ionic gap (Ec), average energy gap (Eg), crystal ionicity (fi) and dielectric constant (ϵ) of binary tetrahedral semiconductors.

scholarly journals Моды волновода с пороговой нелинейностью

2020 ◽  
Vol 46 (16) ◽  
pp. 43
Author(s):  
С.Е. Савотченко
Keyword(s):  
Dielectric Constant ◽  
Optical Properties ◽  
Surface Waves ◽  
Nonlinear Optical ◽  
Layer Structure ◽  
Finite Thickness ◽  
Critical Value ◽  
Field Structure ◽  
Finite Width ◽  
Border Regions

A three-layer structure consisting of a nonlinear optical medium with a stepwise change in the dielectric constant inside which there is a dielectric layer of finite thickness is considered. The surface waves of two types of symmetry with a special field structure can propagate along the layers. Domains of finite width with different optical properties in the border regions in a nonlinear medium are formed. The formation of domains, as well as the existence of surface waves, occurs at interlayer thicknesses not exceeding a certain critical value.

scholarly journals Annealing Effect on Some Optical Properties of Cr2O3 Thin Films Prepared by Spray Pyrolysis Technique

2011 ◽  
Vol 8 (2) ◽  
pp. 561-565
Author(s):  
Baghdad Science Journal
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Spray Pyrolysis ◽  
Annealing Temperature ◽  
Spray Pyrolysis Technique ◽  
Annealing Effect ◽  
Before And After

Cr2O3 thin films have been prepared by spray pyrolysis on a glass substrate. Absorbance and transmittance spectra were recorded in the wavelength range (300-900) nm before and after annealing. The effects of annealing temperature on absorption coefficient, refractive index, extinction coefficient, real and imaginary parts of dielectric constant and optical conductivity were expected. It was found that all these parameters increase as the annealing temperature increased to 550°C.

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