</p> A study of the quadrupole interactions of Ta181 in a polycrystalline hafnium dioxide environment is described in this work. A general introduction to the concepts of angular correlations in nuclear physics is given in Chapter 1 followed by the main outlines of the theory of quadrupole interactions. Instrumental effects involved in the measurement of such an interaction and the analysis of data using Fourier transform methods are discussed. Descriptions of the structure of HfO2 , the factors involved in attaining short time resolutions in timing and the experimental system and methods used in the study are given. The final two chapters contain the results and conclusions with comparison with results from other works.</p> / Thesis / Master of Science (MSc)

The problem of the quadrupole interaction occurring in a vibrating-rotating C₃v symmetric top molecule has been studied in detail. The quadrupole interaction has been treated as another perturbation term to a general frequency expression accounting for the vibrating-rotating interaction of the molecule so that a complete frequency formula is obtained for both interactions, and from which hyperfine spectral components are predicted and measured. The hyperfine transitions in the ground, and v₈=1 and v₈=2 excited vibrational states of the ¹³C isotopes of methyl cyanide have been investigated in the frequency range 17-72 GHz, primarily in the low J transitions (0≤J≤3). The study of the ground state of isotope i3CH3i3CN, and the v₈=1, v₈=2 excited vibrational states for all the isotopes have been conducted here for the first time. A substantial perturbation has been discovered and discussed at the ΔJ=3→4 transitions within the Kl=1 sets in the v₈=1 mode for isotopes ¹³CH₃CN and CH₃¹³CN. A total of 716 hyperfine transitions have been assigned from measurements, only 7 of which have been measured previously. A total of 84 molecular constants have been reported; 70 of these constants are derived for the first time from microwave data.