The fractions of polarized positive muons thermalizing in diamagnetic environments (fD) and as muonium atoms (fM) have been measured in gas phase water, methanol, hexane, cyclohexane, tetramethylsilane, and the chloro-methanes. In almost every case, fM=0.8 and f=0.2, in contrast to the corresponding fractions measured in condensed media where PM=0.2 and PD=0.6. Unlike condensed phases, there is generally no "lost" polarization in the vapors. Any missing fraction is understood in terms of hyperfine dephasing of Mu during thermalization; a distinctly gas phase effect which disappears at moderately high pressures. Carbon tetrachloride
is anomalous in having an unusually low muonium fraction (fM=0.5) in the vapor, but having no muonium in the liquid phase (PD=1.0). Furthermore, the vapor also has a true missing fraction while the liquid does not.
The vapor phase results are interpreted in terms of a hot atom/ion reaction model giving either pressure independent
yields (fD) as seen in water and the chloro-methanes or pressure dependent values as measured in the hexanes and TMS. That interpretation indicates that hot atom reactions do not account for more than about 30% of the much larger diamagnetic fractions seen in condensed phases, suggesting that radiation-induced spur effects are predominant in determining
thermal fractions in condensed media. / Science, Faculty of / Chemistry, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/24470 |
| Date | January 1984 |
| Creators | Arseneau, Donald Joseph |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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