New classes of luminescent transition metal complexes, including the systems of rhenium(I) tricarbonyl diimine, cyclometalated iridium(III) diimine, cyclometalated rhodium(III) diimine, ruthenium(II) diimine and ruthenium(II) terpyridine complexes tethered with rhodamine moieties, have been synthesized. The X-ray crystal structure of one of the cyclometalated rhodium(III) diimine complexes with rhodamine pendants, [Rh(SPLC2N2)(ppy)2](PF6) has been determined. The molecular structure of [Rh(SPLC2N2)(ppy)2](PF6) showed a distorted octahedral geometry and the rhodamine moiety was found in a spirolactam closed-ring form. All of them were found to exhibit emission in fluid solution. The emissions of rhenium(I) tricarbonyl diimine and ruthenium(II) polypyridyl complexes are derived from the triplet metal-to-ligand charge transfer (3MLCT) excited state, i.e. from dπ orbital of the rhenium(I) or ruthenium(II) metal center to the π* orbital of the diimine ligand; while that of cyclometalated iridium(III) diimine complexes is (3MLCT) [dπ(Ir) → π*(N^N)] and that of cyclometalated rhodium(III) diimine complexes involves the (3IL) [π → π*(N^C)] excited state, probably mixed with (3MLCT) [dπ(Rh) → π*(N^C)] character. The cation-binding properties of these complexes toward alkali, alkaline-earth and transition-metal cations were investigated by electronic absorption and emission spectrophotometries. Some of them were found to exhibit new low-energy absorption and emission bands, characteristic of the rhodamine absorption and emission, with high selectivity and sensitivity for certain transition metal cations. A series of rhodamine-appended Schiff base organic compounds has also been synthesized in order to explore their capability as luminescent lanthanide ion sensors. The lanthanide ion binding properties of one of the compounds in acetonitrile were examined. Upon addition of lanthanide ions, new intense low-energy electronic absorption and emission bands were also observed, characteristic of the rhodamine absorption and emission, demonstrating its lanthanide ion sensing behaviour. / published_or_final_version / Chemistry / Master / Master of Philosophy

Element abundance trends with overall metallicity contain vital clues to the formation and evolution of the Galaxy. Abundances may be used to elucidate nucleosynthesis mechanisms and to ascertain rates of Galactic enrichment. To obtain accurate abundances, several crucial inputs such as high-quality spectroscopic observations, rigorous calculations of line transfer, and precise atomic data (e.g. transition probabilities) are necessary. The current work endeavors to improve abundance values for key elements with a four-fold approach: accumulation of hundreds of high-resolution stellar spectra in order to commence a systematic and thorough Manganese abundance derivation in cluster and halo field stars; re-determination of the neutral chromium oscillator strengths and application of this data to stellar abundance analyses; modification of a radiative line transfer code in order to yield accurate abundances from evolved stars; and semi-empirical derivation of transition probabilities to allow for the utilization of spectral features in the red visible and infrared wavelength ranges for abundance determinations. The first comprehensive investigation of manganese in globular clusters is done in this work. A subsolar Mn abundance trend for both halo globular cluster and field stars is found. The analysis shows that for the metallicity range -0.7>(Fe/H)>-2.7 stars of 19 globular clusters have a a mean relative abundance of <(Mn/Fe)>= -0.37±0.01 (σ=0.10), a value in agreement with that of the field stars: <(Mn/Fe)>= -0.36± 0.01 (σ=0.08). Remarkably, the <(Mn/Fe)> ratio remains constant in both stellar populations over a 2 orders of magnitude span in metallicity. Next, the present study employed branching fraction measurements from Fourier transform spectra in conjunction with published radiative lifetimes to determine transition probabilities for 263 lines of neutral chromium. These laboratory values are used to derive a new photospheric abundance for the Sun: log [element of](Cr I)⊙= 5.64±0.01 (σ=0:07). In addition, oscillator strengths for singly-ionized chromium recently reported by the FERRUM Project are employed to determine: log [element of](Cr II)⊙ = 5.77±0.03 (σ= 0.13). No indications of departures from LTE are found in the neutral chromium abundances. The current work then takes advantage of the fact that transition metals exhibit relatively pure LS coupling and employs standard formulae to yield semi-empirical oscillator strengths. These data were then compared to experimental gf values in order to assess accuracy. Finally, this study undertakes a new abundance investigation of the RGB and RHB stars of the M15 globular cluster. A detailed examination of the both the metallicity and n capture elements is performed. This work appears to confirm that star-to-star abundance variations do occur among the M15 giants (which was initially observed by Sneden et al. 1997, 2000). / text

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published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

In longitudinal studies, observational units (commonly referred to as individuals) drawn from some population of interest are followed prospectively over time, and measurements from each individual are taken repeatedly at different points in time with the ultimate goal of characterizing the important features of the population. Longitudinal data naturally arise in many areas of study, where the characterization of the population may be achieved by investigating the effects of covariates on a response. Two or more correlated responses from each individual are also common in longitudinal studies, giving rise to multivariate longitudinal data. For example, the National Longitudinal Survey of Children and Youth (NLSCY) is a long-term study to observe the development of Canadian children. In this survey, measurements about factors influencing a child's social, emotional and behavioral development are collected over time; anxiety and aggression reported for each child in this study may be considered as two response variables to characterize the emotional and behavioral development of children. Since in longitudinal studies, information is collected repeatedly from each individual over time, the occurrence of an event at a particular time point may increase/decrease the likelihood of the occurrence of another event in future. Failure to take into account this phenomenon in analyzing longitudinal data may lead to erroneous conclusion. Moreover, repeated responses (e.g., anxiety and aggression) from an individual may exhibit correlation over time. Separate analyses of such multivariate longitudinal responses ignore this correlation, and as a result, cannot reveal the potential association among the responses which could be of paramount importance in many applications. Therefore, analysis of multivariate longitudinal data requires substantial extension of the standard longitudinal methods. In this thesis, we describe a methodology based on the transition models for multivariate longitudinal binary data to address the transitional behavior between two states characterized by binary responses for two different responses (i.e., two processes). Transitional analysis of multivariate longitudinal binary data can address the longitudinal association within processes and enable marginal interpretation of covariate effects. In addition, estimation and inference of the association between the processes can also be achieved via such models. We illustrate this approach with an application to the NLSCY data, where anxiety and aggression (two correlated responses) are modeled as a function of covariates (gender, depression of person most knowledgeable, number of siblings and family status) to identify their effects on behavioral development of Canadian children. In addition, the extent and direction of the association between two responses are estimated. Gender of the child is found statistically significant for both directions of transition, i.e., from low to high and high to low, of aggression. On contrary, gender of the child is found statistically not significant for both transitions of anxiety. Meanwhile, depression of person most knowledgeable is found marginally significant in the high to low direction for aggression. For association parameters, all four directions of associations between anxiety and aggression are found statistically significant.

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No description available.