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Title:Experimental and Theoretical Studies of Nuclear Generation of Ozone and Its Photolysis Into Singlet Delta Oxygen
Author(s):Elsayed-Ali, Hani Elsayed
Department / Program:Electrical Engineering
Discipline:Electrical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Electronics and Electrical
Abstract:A series of measurements of O(,3) yield in nuclear induced O(,2) and O(,2)-SF(,6) discharges are reported. The discharges were created by bombardment with energetic particles from the ('10)B(n,(alpha))('7)Li reaction. Continuous irradiation at dose rates of 10('15) - 10('17) eV(.)cm('-3)(.)s('-1) and pulsed irradiation ((TURN)10 ms FWHM) at a peak dose rate of (TURN)10('20) eV(.)cm('-3)(.)s('-1) were conducted. At the lower dose rates, SF(,6) addition generally increased the ozone yield due to the slowing of ozone destruction by negative oxygen and ozone ions. In contrast, at the high dose rates, SF(,6) addition decreased the observed ozone concentration due to its suppression of atomic oxygen formation by ion-ion recombination. A numerical model was developed and applied to experimental conditions. The steady-state ozone concentration was found to be limited by the reaction O(,3)('-) + O(,3) (--->) 2 O(,2) + O(,2)('-) for which a rate coefficient of (TURN)1 x 10('-12) cm('3)(.)s('-1) gives a good fit to the experimental data. A simplified analytical model of steady-state conditions was used to predict model sensitivity to various parameters. In addition to dose rate effects, pressure and temperature effects on ozone production were discussed.
The present study was extended to noble gas (He, Ne, and Ar)-O(,2) and noble gas - O(,2)-SF(,6) mixtures. Without SF(,6), steady-state ozone concentrations were found to be about an order of magnitude lower than that observed for oxygen at similar dose rates. Addition of SF(,6) was found to significantly increase the steady-state ozone concentration (3-6 times) in noble gas-O(,2) mixtures. The developed models were amended to study noble gas-O(,2) discharges. Dose rate and pressure effects were also studied.
A detailed computer model of ultraviolet irradiation of O(,3)-O(,2)-noble gas mixtures was presented. Dependence of O(,2)(a('1)(DELTA)(,g)) yield on various parameters was investigated. Conditions needed to create O(,2)(a('1)(DELTA)(,g)) concentrations sufficient for pumping an atomic iodine laser were identified. The model was tested by applying it to data on quantum yield of ozone decomposition for various mixtures and by observation of the absolute O(,2)(a('1)(DELTA)(,g)) concentrations generated under various conditions.
Issue Date:1985
Description:294 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.
Other Identifier(s):(UMI)AAI8521758
Date Available in IDEALS:2014-12-15
Date Deposited:1985

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