Radiation Induced Impurity Precipitation in Mgo

1985 ◽  
Vol 60 ◽  
Author(s):  
S. Clement ◽  
E. R. Hodgson
Keyword(s):  
Absorption Band ◽  
Optical Absorption ◽  
Dose Rate ◽  
Reduction Process ◽  
High Dose ◽  
Optical Absorption Band ◽  
Enhanced Diffusion ◽  
Dose Rates ◽  
Radiation Enhanced Diffusion ◽  
Radiation Induced

AbstractIn MgO irradiated at high dose rates and high temperatures with 1.8 MeV electrons, a suppression of the Fe3+ optical absorption band at 290 nm is observed. This suppression, a function of both dose rate and temperature, is consistent with a reduction process induced by oxygen displacement damage. Both thermal and radiation enhanced diffusion are involved and lead to the formation of iron containing precipitates. Similar results have been obtained for Ni2+.

Prediction of High Dose Ion Implantation Profiles as Influenced by Radiation Induced Transport and Sputtering

1985 ◽  
Vol 45 ◽  
Author(s):  
M. Rangaswamy ◽  
D. Farkas
Keyword(s):  
Probability Distributions ◽  
Practical Interest ◽  
High Dose ◽  
High Fluence ◽  
Enhanced Diffusion ◽  
Preferential Sputtering ◽  
Radiation Enhanced Diffusion ◽  
Defect Probability ◽  
Radiation Induced ◽  
Effects Of Radiation

ABSTRACTVarious models for predicting high fluence ion collection profiles are reviewed. Recent calculations based on the diffusion approximation are described. The solute and defect probability distributions are calculated by a MONTECARLO code, TRIM. The method takes into account the effects of sputtering, including preferential sputtering of one of the components, and lattice dilation. In addition, the effects of radiation enhanced diffusion and radiation induced segregation are also considered. The calculations include the coupling of solute and defect fluxes. The described formalism can account for observed maximum attainable concentrations and distributions in high fluence implantation conditions of practical interest.

Radiological Control of Gold Octahedral and Prism Nanoparticles

2007 ◽  
Vol 1056 ◽  
Author(s):  
Tina M. Nenoff ◽  
Jason C. Jones ◽  
Paula P. Provencio ◽  
Donald T. Berry
Keyword(s):  
Dose Rate ◽  
High Dose Rate ◽  
Pure Gold ◽  
High Dose ◽  
Visible Absorption ◽  
Dose Rates ◽  
Radiation Induced ◽  
Radiological Control ◽  
Uv Visible ◽  
Short Time

ABSTRACTWe report on a fundamental morphology growth of gold-based nanoparticles by solution radiolysis. Radiolysis of pure gold-polymer solutions of different dose rates and aging time is examined. A detailed description will be presented of the experimentation, testing and analysis. In particular, we will present data on the formation of gold nano-octahedra and -prism particles. The γ-irradiations were carried out with a 60Co source of 1.345 × 105 Ci (Sandia National Laboratories Gamma Irradiation Facility (GIF). Nanoparticle characterization techniques included are UV-vis and TEM. Similar to what has been seen in earlier silver nanoparticle studies, dose rate dictates the size of nanoparticles formed. At high dose rate, all reducing species are produced and scavenged within a short time, and then coalesce into separate nanoparticles. At low dose rate, the coalescence process is faster than the production rate of the reducing radicals. The reduction of radicals occurs mainly on clusters already formed. The differences in the morphologies result from a combination of dose rate, aging and lack of radical scavengers (e.g. isopropyl alcohol), resulting in either gold nano-spheres, octahedral or prism nanoparticles. The progressive evolution with dose rate of the UV-visible absorption spectra of radiation-induced metal clusters is discussed.

A Positive-Ion Reaction Mechanism for the Radiation Induced Oxidation of Carbon Monoxide in the High Dose Rate Radiolysis of CO–O2 Mixtures

1972 ◽  
Vol 50 (21) ◽  
pp. 3508-3514 ◽  
Author(s):  
C. Willis ◽  
A. W. Boyd ◽  
P. E. Bindner
Keyword(s):  
Dose Rate ◽  
Low Dose ◽  
High Dose Rate ◽  
High Dose ◽  
Total Oxygen ◽  
Dose Rates ◽  
Electron Scavenger ◽  
Radiation Induced ◽  
A Chain ◽  
Positive Ion

Carbon dioxide and ozone yields have been measured in the irradiation of CO–O2 mixtures with single pulses of electrons. The yields of CO2 at 2 × 1027 ev g−1 s−1 are large G(CO2) = 15 ± 1 from 20–60% O2. These decrease by ∼50% at 1028 eV g−1 s−1. Although the results are somewhat irreproducible the addition of c-C4F8, an electron scavenger, increases these CO2 yields at both dose rates by up to a factor of 15. They are reduced to G(CO2) < 2 by the addition of positive ion scavengers. These results are consistent with a chain reaction similar to that proposed for low dose rate studies involving [Formula: see text], [Formula: see text], and [Formula: see text] as chain carriers.The ozone yields are consistent with a total oxygen atom yield of G(O) = 1.4 in pure CO from neutral processes.

Measuring Radiation Enhanced Diffusion Through in situ Ion Radiation Induced Sintering of Oxide Nanoparticles

2021 ◽  
Author(s):  
Nathan J. Madden ◽  
Samuel A. Briggs ◽  
Diana Perales ◽  
Timothy J. Boyle ◽  
Khalid Hattar ◽  
...  
Keyword(s):  
Oxide Nanoparticles ◽  
Enhanced Diffusion ◽  
Radiation Enhanced Diffusion ◽  
Radiation Induced

The effects of high dose rates of ionizing radiations on solutions of iron and cerium salts

1960 ◽  
Vol 255 (1283) ◽  
pp. 490-508 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Dose Rate ◽  
Ferrous Sulphate ◽  
High Dose ◽  
Oh Radicals ◽  
Dose Rates ◽  
Reaction Zones ◽  
Constant Dose ◽  
Ceric Sulphate ◽  
Ionizing Radiations

The electron beam generated by a 15 MeV linear accelerator has been employed to induce reactions in aerated aqueous solutions of 1 to 25 mM ferrous sulphate, and of 0⋅1 to 1 mM ceric sulphate. The radiation was delivered in pulses of 1⋅3 μ s duration and over a range of dose rates from 0⋅5 to 20000 rads/pulse. Radiation yields at constant dose rate were compared with the aid of a chemical dose monitor. A system of two thin, widely spaced, irradiation vessels was employed to determine the variation of yield of any one system over successive known ranges of dose rate. The yield of ferric sulphate in the iron system was found to decrease with increasing dose rate in the range 0⋅01 to 10 krads/pulse by an overall factor of 0⋅85, and was appreciably dependent on the initial concentrations of dissolved oxygen and of ferrous sulphate at high dose rates. Yields of hydrogen and of hydrogen peroxide were practically independent of dose rate. The observations have been interpreted on the basis of inter-radical reactions which occur when the reaction zones of neighbouring clusters overlap. The following reactions can account for all the data: OH + Fe 2+ → Fe 3+ + OH ¯ , (1) H + O 2 → HO 2 , (2) H + OH → H 2 O. (7) The values k 1 / k 7 = 0⋅0062, and k 2 / k 7 = 0⋅22 are reasonably consistent with the observations. In the ceric sulphate system the yield of cerous sulphate increases progressively over the range 0⋅01 to 10 krads/pulse by an overall factor of 1⋅4. The data accord with the view that at high dose rates OH radicals react with them selves ultimately to form hydrogen peroxide, in competition with their normal reaction with cerous sulphate.

scholarly journals Photocatalytic NO removal over calcium-bridged siloxenes under ultraviolet and visible light irradiation

2018 ◽  
Vol 47 (20) ◽  
pp. 7070-7076 ◽  
Author(s):  
Haruo Imagawa ◽  
Xiaoyong Wu ◽  
Hiroshi Itahara ◽  
Shu Yin ◽  
Kazunobu Kojima ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Absorption Band ◽  
Optical Absorption ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Light Irradiation ◽  
Ultraviolet Region ◽  
No Removal ◽  
Optical Absorption Band

Ca-Bridged siloxenes with a wide optical absorption band from the visible to ultraviolet region exhibited photocatalytic activity for NO removal.

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