Scanning Tunneling Microscopy (STM) has been used to study the physisorption and chemisorption behaviour for three simple organic haloalkanes; 1,5 Dichloropentane (DCP), Bromomethane (CH3Br) and Chloromethane (CH3Cl)) on Si(100) 2x1, at temperatures ranging from 270 K to room temperature. The results were interpreted by Density Functional Theory (DFT) performed by collaborators at McGill University and the University of Liverpool. Physisorbed molecules of DCP were found to self assemble into stable lines aligned predominantly perpendicular to the Si dimer pair rows on the surface. A novel mechanism for line formation of Dichloropentane, termed, Dipole Directed Assembly (DDA), was elucidated by DFT calculations. For CH3Br three different patterns of dissociative attachment of reaction products (CH3 and Br/Cl) were observed, and assigned to three reaction pathways. These experimentally determined relative yields were used to obtain differences in reaction activation energy, Delta Ea, between the reaction pathways. These, in turn, were compared with computed differences in reaction barriers, Delta Eb, obtained ab initio for the same pathways by DFT. For CH3Cl, two single-molecule patterns of attachment were found, and a new reaction pathway for attaching CH3Cl in long chains of alternating CH3 and Cl was discovered. The mechanisms for chain growth were determined experimentally by examination of single molecular steps. This mechanism was explained ab initio by DFT to be the result of relative barrier heights for the possible chain-growth pathways.

Thesis (Ph. D.) in Forest Resources--University of Maine, 2003. / Includes vita. Includes bibliographical references (leaves 161-176).

Thesis (Ph.D.)--University of Texas at Arlington, 2008.

Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xii, 103 p.: ill. (some col.). Includes abstract and vita. Advisor: Heather Allen, Dept. of Chemistry. Includes bibliographical references (p. 88-94).

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A method for representing solid-liquid sorption behavior of solutes by a two step equilibrium is shown to correlate well with observed sorption behavior. By fitting a three term expression to isotherm plots of solute surface concentration vs. the concentration in the bulk solvent the two distribution constants as well as the maximum sorption capacity are determined. Isotherms for hydrocarbon-modified silica are determined for various solvents and solutes. Interpretation of sorption behavior is presented in terms of values determined for sorption capacity and the distribution coefficients. The isotherm model parameters are shown to correlate to the chromatographic retention parameter, k'. Sorption capacity is proposed as a more meaningful representation of the chromatographic phase ratio. Reversed-phase chromatographic retention and efficiency are shown to be affected by ion modifiers as well as the temperature history of a system when a totally aqueous mobile phase is used. The dynamic nature of the octylsilane modified surface is discussed in terms of changes which are induced by cations exchanged on the silica surface and imbibed organic solvent in the bonded hydrocarbon chain previously used to condition the surface. Both polar and non-polar solutes are used and their retention behavior allows interpretation of changes in specific regions of the surface. The development of magnetic Field-Flow Fractionation (Magnetic FFF), a separation technique for small magnetic particles, is described as well as the parameters which affect such separations. The use of a FFF device to characterize small particle suspensions is demonstrated. The change in turbidimetric response of iron oxide particle suspensions in a spectrophotometric device under the influence of a magnetic field is interpreted in terms of the difference in particle shape.

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