![Laser Fluorescence Spectroscopy of Sputtered Uranium Atoms. [Mechanisms, 3 KeV]. PDF](https://books.google.com/books/content/images/frontcover/G656AQAACAAJ?fife=w80-h100)
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Languages : en
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Laser induced fluorescence (LIF) spectroscopy was used to study the sputtering of 99.8% 238U metal foil when bombarded by normally incident 500 to 3000 eV Ne, Ar, Kr+, and O2+. A three-level atom model of the LIF processes is developed to interpret the observed fluorescent emission from the sputtered species. The model shows that close attention must be paid to the conditions under which the experiment is carried out as well as to the details of the collision cascade theory of sputtering. Rigorous analysis shows that when properly applied, LIF can be used to investigate the predictions of sputtering theory as regards energy distributions of sputtered particles and for the determination of sputtering yields. The possibility that thermal emission may occur during sputtering can also be tested using the proposed model. It is shown that the velocity distribution (either the number density or flux density distribution, depending upon the experimental conditions) of the sputtered particles can be determined using the LIF technique and that this information can be used to obtain a description of the basic sputtering mechanisms. These matters are discussed using the U-atom fluorescence measurements as a basis. The relative sputtering yields for various incident ions on uranium were also measured for the first time using the LIF technique. A surprisingly high fraction of the sputtered uranium atoms were found to occupy the low lying metastable energy levels of U(I). The population of the sputtered metastable atoms were found approximately to obey a Boltzman distribution with an effective temperature of 920 +- 100°K. 41 references.
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Category : Power resources
Languages : en
Pages : 1634
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Category : Nuclear energy
Languages : en
Pages : 1210
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Languages : en
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The use of laser radiation to study the sputtering process is of relatively recent origin. Much has been learned from this work about the basic physics of the sputtering process itself through measurements of velocity and excited state distributions of sputtered atoms and the effects of adsorbates on substrate sputtering yields. Furthermore, the identification, characterization, and sensitive detection of sputtered atoms by laser spectroscopy has led to the development of in situ diagnostics for impurity fluxes in the plasma edge regions of tokamaks and of ultrasensitive methods (ppB Fe in Si) for surface analysis with ultralow (picocoulomb) ion fluences. The techniques involved in this work, laser fluorescence and multiphoton resonance ionization spectroscopy, will be described and illustrations given of results achieved up to now. 55 refs., 5 figs., 1 tab.
Author: Fred A. Blum
Publisher: Springer
ISBN:
Category : Science
Languages : en
Pages : 410
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Author: R A W Johnstone
Publisher: Royal Society of Chemistry
ISBN: 1847556639
Category : Science
Languages : en
Pages : 370
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Specialist Periodical Reports provide systematic and detailed review coverage of progress in the major areas of chemical research. Written by experts in their specialist fields the series creates a unique service for the active research chemist, supplying regular critical in-depth accounts of progress in particular areas of chemistry. For over 80 years the Royal Society of Chemistry and its predecessor, the Chemical Society, have been publishing reports charting developments in chemistry, which originally took the form of Annual Reports. However, by 1967 the whole spectrum of chemistry could no longer be contained within one volume and the series Specialist Periodical Reports was born. The Annual Reports themselves still existed but were divided into two, and subsequently three, volumes covering Inorganic, Organic and Physical Chemistry. For more general coverage of the highlights in chemistry they remain a 'must'. Since that time the SPR series has altered according to the fluctuating degree of activity in various fields of chemistry. Some titles have remained unchanged, while others have altered their emphasis along with their titles; some have been combined under a new name whereas others have had to be discontinued. The current list of Specialist Periodical Reports can be seen on the inside flap of this volume.
Author: Robert Allen Weller (Jr)
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Category : Electronic dissertations
Languages : en
Pages : 196
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The energy spectra of 235U atoms sputtered from a 93% enriched 235U metal foil and a hot pressed 235U02 pellet by an 80 keV 40Ar beam have been measured in the range 1 eV to 1 keV. The measurements were made using a mechanical time-of-flight spectrometer in conjunction with the fission track technique for detecting 235U. The design and construction of this spectrometer are discussed in detail, and its operation is mathematically analyzed. The results of the experiment are discussed in the context of the random collision cascade model of sputtering. The spectrum obtained by the sputtering of the 235U metal target was found to be well described by the functional form E(E+E[subscript b])−2̇.77, where E[subscript b] = 5.4 eV. The 235U02 target produced a spectrum that peaked at a lower energy (~ 2 eV) and decreased somewhat more rapidly for E>~ 100 eV.
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Category : Physics
Languages : en
Pages : 1812
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Author: H. Rebel
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Languages : de
Pages : 29
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Author: Masaki Ohba
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Category :
Languages : ja
Pages : 16
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