Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 17, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Reid Smeda. Includes bibliographical references.

Thesis (M.A.)--Eastern Illinois University, 2010. / Includes bibliographical references (leaves 81-85).

Call number: LD2668 .T4 1958 W51

Graduation date: 1999

Call number: LD2668 .T4 1946 H4 / Master of Science

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 180-190).

Thesis (M.S.)--Oregon State University, 1996. / Typescript (photocopy). Includes bibliographical references (leaves 108-123). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 188-206).

Methyl halides are trace gases with both natural and anthropogenic origins. Once generated, these gases transport chlorine and bromine into the stratosphere, where they play an important role in ozone depleting catalytic cycles. The Florida Everglades is one location where methyl halide emissions have been proposed to be elevated due to high primary production and ionic halogens. This region also provides a unique study environment due to salt water intrusions, which occur during storm or low marsh water level-high tide events. The purpose of this research was twofold. First, quantification of methyl chloride (CH3Cl) and methyl bromide (CH3Br) production from periphyton mats on a temporal scale was needed. Secondly, to determine how varying concentrations of salinity affect CH3Cl and CH3Br production originating from calcareous periphyton mats within the Everglades. Periphyton was exposed to continuous 12 hour dark/light cycles in varying concentrations of salt water (0, 0.1, 1, 5, and 10 parts per thousand). All water samples were analyzed to determine the production rate of CH3Cl and CH3Br in periphyton samples using a gas chromatograph coupled with an electron capture detector (GC-ECD). Periphyton mats were found to be a producer of CH3Cl in all freshwater (0 parts per thousand) trials and sampling times; however, results from CH3Br analysis found production rates that suggest consumption occurred in the majority of the 0 parts per thousand trials. Production rates for CH3Cl ranged from 0.077 to 0.109 g-1hr-1 after 24 hours, 0.027 to 0.073 pM g-1hr-1 after 48 hours, and 0.034 to 0.047 pM g-1hr-1 after 72 hours. Production rates for the CH3Br freshwater experiments ranged from -0.00025 to 0.00185 pM g-1hr-1 after 24 hours, -0.00022 to -0.00078 pM g-1hr-1 after 48 hours, and -0.00042 to -0.00061 pM g-1hr-1 after 72 hours. This research has also shown that increased salinity does have a significant positive effect on the production of CH3Cl and CH3Br from calcareous periphyton mats, which is important in areas that could be prone to salt water intrusions or rising sea levels due to global climate change.

The main purpose of this Thesis is the experimental characterization of the electronic and geometric structures of objects called clusters. A cluster consists of a finite group of bound atoms or molecules. Due to its finite size, it may present completely different properties than those of the isolated atom and the bulk. The clusters studied in this work are constituted by rare-gas atoms, organic molecules, and metal atoms. Intense cluster beams were created using either an adiabatic expansion source or a gas-aggregation source, and investigated by means of synchrotron radiation based photoelectron spectroscopy. The reports presented in this Thesis may be divided into three parts. The first one deals with results concerning homogeneous molecular clusters (benzene- and methyl-related clusters) highlighting how molecular properties, such as dipole moment and polarizability, influence the cluster structure. The second part focuses on studies of solvation processes in clusters. In particular, the adsorption of polar molecules on rare-gas clusters is studied. It is shown that the doping method, i.e. the technique used to expose clusters to molecules, and the fraction of polar molecules are important factors in determining the location of the molecules in the clusters. Finally, a summary of investigations performed on metal clusters is presented. The applicability of solid state models to analyse the cluster spectra is considered, and the differences between the atomic, cluster and solid electronic structures are discussed.