Photon and secondary ion emission induced by particle bombardment of solids /
A novel experimental method has been developed and used to
| Main Author: | |
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1994.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=741965591&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | A novel experimental method has been developed and used to simultaneously study multiple secondary signals produced by the impact of monatomic and polyatomic ions onto solid surfaces. This method is a coaxial system based on the time-of-flight mass analysis of primary ions which are produced by a spontaneous desorption based ion source. H-, low mass organic, and (CSI)nl- (n = 0 - 3) ions in the 20 - 45 keV energy range have been used as primary ions in time- of-flight secondary ion mass spectrometry (ToF-SIMS) experiments to: (i) study the relationship between secondary ions and photons emitted from a surface and (ii) probe the partition of energy deposited into the electronic and nuclear systems of the target by the primary ion. All experiments are performed in the event-by-event analysis mode so that secondary ions and photons from individual collision cascades can be studied and readily compared. Secondary ion and photon yields from Csl have been measured for a number of monoatomic and polyatomic projectiles. For the energy range examined, secondary ions and photons are produced independently of each other through different mechanisms. Secondary ion emission is strongly dependent upon the complexity of the primary ion, i.e., monoatomic or polyatomic. However, photon emission appears to be independent of the primary ion's complexity and depends primarily upon the velocity of the primary ion. Unlike the secondary ion yields, no yield enhancements for the photons have been observed due to polyatomic primary ions. Light was analyzed using time resolved and wavelength analysis. For Csl samples, photons originate from within the sample bulk and stem from the radiative decay of self trapped excitons produced directly by the primary ions and indirectly by recoiling target atoms. The number of photons emitted per primary ion impact (intensity) is proportional to the number of generated self-trapped excitons, and the luminescence lifetime is inversely proportional to the density of self-trapped excitons. The emission wavelength is exclusively determined by the chemical composition of the sample. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xvii, 207 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |