| Summary: | Positive muons are produced at TRIUMF as pion decay products and form muo
nium atoms in media such as water during their two microsecond lifetime. Muo
niuin is a hydrogen—like atom with virtually the same Bohr radius and ionization
energy as 1H, 2H and 3H, but with a mass one—ninth that of 1H. Its reactions
toward solutes are studied by μSR (the muon spin rotation) and LCR (muon
level crossing resonance spectroscopy).
In this thesis, the reactions of mnuonium with some substituted aromnatics and
N-heterocyclic compounds were studied. Reaction rate constants were measured
in many cases, and products were identified as mnuonated free radicals formed
by muonium addition to a ring-C. Muon hyperfine coupling constants of some
muonated cyclohexadienyl-type radicals and all muonated mono- and diazine
radicals studied here were determined. The LCR spectra of muonated radicals
were recorded and the resonance signals were assigned to particular nuclei of
these radicals. Radical isomer distributions and partial rate constants for mono
substituted benzenes and N-heterocyclic compounds were estimated. π-electron
densities and radical localization energies of neutral aromnatics were calculated
by the Huckel MO method. For N-containing compounds LUMO levels as well
as these parameters were also calculated by the same method. It was found that
there exists a good correlation between partial rate constants and radical localization energies, which implies that muonium addition rates in these systems are
mainly governed by an activation barrier proportional to the radical localization
energies of the reactants. === Science, Faculty of === Chemistry, Department of === Graduate
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