The overall goal of this research is a comprehensive characterization of self-assembled alkanethiol monolayer films at Ag and Au surfaces. A combination of surface Raman spectroscopy and electrochemistry is employed to study several important aspects of these films. Raman vibrational assignments for a series of n-alkanethiols (n = 4, 5, 8, 9, 10, 12, 16, and 18 for C(n)H(2n+1)SH) are determined in the spectral regions from 600 to 1300 cm⁻¹ and 2800 to 3000 cm⁻¹. Particular emphasis is given to the trans (T) and gauche (G) ν(C-S) and ν(C-C) bands and the ν(C-H) bands. Surface Raman spectra of n-alkanethiol films at electrochemically roughened and mechanically polished, polycrystalline Ag and Au surfaces are presented. Strong enhancements of surface Raman scattering are realized at roughened surfaces, while less enhancement is observed at the mechanically polished surfaces. The conformational order of these films at these surfaces is evaluated by the determination of T and G bands present in the spectra. The orientation of these films at Ag and Au is determined through the use of surface Raman selection rules. A method is developed for the determination of orientation of C-S and C-C bonds and methyl groups. The orientations deduced using the spectral results from each of these regions are found to be self-consistent. Different orientations are deduced for alkanethiol films at Ag and Au surfaces and are proposed to be influenced by metal-S bonding. The orientations can be altered in the electrochemical environment by control of the applied potential of these metal substrates. The potential-dependent behavior is correlated with the potential of zero-excess charge (PZC) of these metals. Defect structure of these films at Ag surfaces with various surface morphologies is evaluated with Pb deposition studies. Gross films defects are evaluated with Pb underpotential deposition and ion penetration is studied with bulk Pb deposition. Finally, surface Raman spectra of monolayer films at non-enhancing surfaces are presented. Spectra for butanethiol at single-crystal Ag surfaces and butanethiol and thiophenol at mechanically polished, polycrystalline Pt surfaces show the utility of Raman spectroscopy for studying films at a variety of surfaces.

In the analysis of solid samples, there are two distinct advantages to performing direct analysis on the solid: (1) minimal sample preparation and (2) avoids potential sample contamination from the reagents used in the dissolution process. The two most common optical techniques for direct solids analysis are arc and spark emission spectroscopy. The most important drawback associated with arc and spark spectroscopy is in the acquistion and interpretation of the spectrum. The development of a custom echelle spectrometer with Charge Injection Device (CID) array detection carried out in these laboratories should be particularly well suited for arc and spark emission spectroscopy. CIDs exhibit many of the best characteristics of photographic film and PMT detection while providing the added advantage of nondestructive readout and Random Access Integration (RAI). This thesis describes the work coupling a spark source to a CID/echelle spectrometer. When properly shielded, the sensitive electronics of the CID function normally in the presence of the spark discharge. The potential for this system to be able to handle the wide variety of spectroscopic situations resulting from the complex spectra typically obtained with this type of excitation is attributed to the flexibility of the instrument which allows the use of alternate line for analysis and internal standard calibration. Additionally, the use of multiple lines has been applied to comparative analysis, monitoring the background for changes in excitation, and determination of the optimum lines to be used for quantification. Effective utilization of the large database of spectral information has lead to the development of sophisticated expert systems such as automated qualitative and semiquantitative analysis routines. Preliminary work with an astigmatism free imaging spectrograph and a Charge Coupled Device (CCD) array detector has shown the ease with which spatial and spectral maps of emission source can be generated. Observation of the spark discharge process in a hope of gaining a clearer picture of the mechanisms of sample excitation seems to be the most rational approach to ultimately obtaining control over the spark process and alleviating the problems associated with sparks excitation.

Centrifugal Partition Chromatography (CPC) is a multistage liquid-liquid countercurrent distribution technique which utilizes rotating teflon cartridges to hold a liquid phase stationary while the other liquid phase is pumped at a constant flow rate. It has been demonstrated to be a valuable technique for the base line separations of families of metal ions such as the platinum group metals (PGM)--Pt, Pd, Rh and Ir. The separations of these metals as their anionic chloro complexes were achieved using the heptane-water phase pair with a stable and relatively inexpensive extractant trioctylphosphine oxide (TOPO) functioning as a ligand in its neutral form and as a cation in its protonated form. A striking feature of the chromatograms of the complexes and ion pairs were their much poorer efficiencies compared to the efficiency of an organic analyte like 3-picoline under identical distribution rations. The inefficiencies of the PGM separations were also a function of the concentrations of the aqueous and organic phase components. These inefficiencies could be attributed to slow kinetics of the back extraction of the complexes and ion pairs and could be used to derive the mechanisms of these slow chemical kinetic steps. A correlation was established for the Pd(II) system between the CPC inefficiencies and the half lives of the slow reactions measured independently by stopped flow in micelles. This correlation was utilized to derive the rate constants for the back extraction of the TOPO complexes and ion pairs of Pt and Ir. The mechanisms of the extraction reactions were derived using the principle of microscopic reversibility based on the mechanisms of the back extraction reactions. This was then used to obtain estimates for the rate constants for the extraction reactions as well. The PGM were thus separated and their equilibrium and kinetics (extraction and back extraction) completely characterized using CPC. This is a significant development with CPC because such complete equilibrium and kinetic characterizations are hard to achieve with conventional liquid chromatographic techniques.

Control of separation processes which occur at solid-liquid interfaces can be achieved by understanding the interactions which occur at these interfaces. Because of its many desirable bulk characteristics, silica is the solid support of choice for many separation applications. Utilizing various differential migration techniques, control of the separation at different silica surfaces was investigated through irreversible chemical modification of the surface, the use of a dynamic modifier, and through physicochemical alteration of the silica surface. A new bonded phase was prepared by reacting γ-(3,4 methylene dioxyphenyl) propyldimethylchlorosilane--synthesized from safrole and dimethylchlorosilane--with porous silica yielding a non-traditional bonded phase which maintained some similarity with traditional alkyl bonded phases while also possessing distinct differences. Through the use of diagnostic chromatography this surface was shown to demonstrate unique selectivity towards polar analytes when compared with an octyl and phenyl surface under the same solvation conditions. A thermal study utilizing diagnostic chromatography was also used to demonstrate the impact of orientation on retention at this surface. The large scale separation of C₆₀ and C₇₀ was accomplished using a batch process utilizing a traditional bonded phase under normal phase condiitons. Both the kinetics and thermodynamics of the separation were improved through the addition of a dynamic modifier to the running solvent. Macroscopic quantities of pure C₆₀ and C₇₀ are readily obtained using this approach. Control of electroosmotic flow in silica capillaries was demonstrated by chemically tailoring the surface with a series of novel silane modifiers. Although changes in electroosmotic flow velocity were observed, the ultimate goal of flow reversal was not achieved. Finally, a new ISRP surface was prepared by monoatomic oxygen treatment of large (63-90μm) irregularly shaped modified silica particles. This new ISRP was evaluated to determine if the more technically demanding but practically useful treatment of high efficiency particles for use in direct injection HPLC should be pursued.

The behavior of water at the modified silica interface was studied with Differential Scanning Calorimetry. A model for the interaction of water with the surface of silica was evolved to include the influence of the silica surface, the modification of the surface with hydrophobic and hydrophilic functional groups, and the presence of organic solvents. Initial studies involved the investigation of the melting behavior of water at the surface of unmodified silica. This was studied as a function of pore size, specific surface area, surface activity and specific pore volume. The perturbation of the water in the near surface region by interactions with the surface silanols and the curvature of the silica surface resulted in the observation of a melting peak was that was significantly different than the bulk water behavior. Changes to this peak were observed as a function of the modification of the silica surface with alkyl chains of varying chain length, and variations in the bonding density of these chains. As a consequence of the modification of the surface, the water was able to interact with only isolated silanol sites and this was reflected in a shift in the melting peaks. The deactivation of the silanol sites occurred both through the formation of the silyl ether linkage to the modifier, and the blocking of the surface by the hydrophobic alkyl chains. The changes in the behavior of water at the modified silica interface in the presence of organic solvents were also investigated. It was found that the ability of the organic solvent to hydrogen bond to the silica surface and with water was the greatest contributor to the changes in the melting behavior of the water. The behavior of water at the silica interface modified with hydrophilic functional groups was investigated. It was found that the functional groups that could hydrogen bond with the water could also influence its melting behavior. As a consequence the layer of water affected by the surface was extended further away from the surface than was observed with unmodified silica.

Studies of the mechanisms and energetics of a variety ion-molecule reactions involving organometallic and organic ions, have been performed using Fourier transform ion cyclotron resonance mass spectrometry (FTMS). The bond activation processes of V⁺, VO⁺, VOH⁺, and VOCH₃⁺ with water and methanol were investigated in detail. All ions are observed to preferentially activate the C-O bond in methanol, however C-H and O-H bond cleavage are also observed. The addition of the oxo, hydroxo, and methoxo ligands is found to significantly effect the intrinsic reactivity of the ions, relative to V⁺. The reactions of V(CO)₅⁻ with a wide variety of molecules have revealed mechanistic details of the oxidative addition and ligand switching reactions. Steric effects are proposed to account for the selective reactivity of V(CO)₅⁻ with alcohols and amines. Studies of ligand substitution reactions support an electron transfer initiated mechanism, implying that V(CO)₅⁻ has a triplet ground state and a trigonal bipyramidal structure. The chlorine atom transfer reactions of V(CO)₅⁻ with chloromethanes display a correlation with C-CI bond strength, suggesting the mechanism is initiated by oxidative addition of the C-C1 bond or involves a direct chlorine atom transfer. The decomposition of metallocarboxylate anions ([M(CO)ₓ₋₁CO₂]⁻) was studied in an effort to understand the production of CO₂ by metal carbonyl compounds, proposed as intermediates in the Water-Gas shift reaction. The nascent [M(CO)ₓ₋₁C0₂]⁻*, formed by nucleophilic addition of 0⁻ to M(CO)ₓ (M=Pe, Cr, V), is observed to undergo exclusive loss of CO₂ without subsequent decomposition of the product metal carbonyl anion (M(CO)ₓ₋₁⁻) The reaction of P AHs with O⁻ and O₂⁻ were studied, to investigate the potential of isomer differentiation by chemical ionization. These reactions are characterized by a number of reactive pathways, demonstrating the ability to distinguish isomers which cannot be differentiated by other ionization techniques. Kinetic energy release measurements of the S(N)2 reactions of F⁻ with CH3CI, C₆H₅CI, and CH₃COCl have been made using KEICR. The F⁻/CH₃Cl reaction results in a non-statistical energy disposal. The reaction is proposed to proceed by a direct mechanism.

Proton induced x-ray emission spectroscopy (PIXE) is a rapid and sensitive analytical technique for the non-destructive simultaneous determination of elemental concentrations above atomic number 11 (sodium) and is the only analytical technique that can determine 20-30 elements nondestructively in a single small sample (≈5 mg) with detection limits of 1- 5 ppm (dry weight). Part I of this dissertation outlines work done on the optimization of instrumental parameters and sample preparation for the analysis of biological tissue. Cultured rabbit renal slices were used as the biological system to demonstrate the use of PIXE analysis. The renal slices were exposed to HgCl₂, CdCl₂, K₂Cr₂0₇, or NaAsO₂ alone or in a mixture. The analysis of biological samples by PIXE provides information on inter-elemental interactions in tissue and body fluids. A computer program for spectrum processing and quantitation, which decomposes overlapped peaks, corrects for thick target matrix effects and calculates results without resorting to the use of standards, is explored. In part II of this dissertation, a convenient method of removing solvent from a benzene extract of graphitic soot containing fullerenes using sublimation, is outlined. Separation of macroscopic quantities of the fullerenes C₆₀ and C₇₀ has been accomplished using a combination of selective precipitation of C₆₀ and chromatography. C₆₀ is selectively crystallized by freezing and thawing a benzene solution of mixed fullerenes, then using the C₇₀ enriched supernatant as starting material in the chromatographic separation of C₆₀ and C₇₀. In the separation scheme, a bed of modified silica sorbent is charged with the fullerene mixture and the fullerenes are eluted using a hexanes/THF mobile phase. The methods of uv-Visible and infrared spectroscopy, as well as high performance liquid chromatography (HPLC) are evaluated for their ability to determine the purity of a C₆₀ or C₇₀ sample.

Chan Lai-Yin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 83-84). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iii / Table of Contents --- p.iv / List of Abbreviations and symbols --- p.viii / List of Appendices --- p.x / List of Figures --- p.xi / List of Tables --- p.xii / Chapter Chapter 1: --- General Introduction --- p.1 / Chapter 1.1 --- Studies of Plant Constituents --- p.1 / Chapter 1.2 --- Extraction of Chemical Ingredients --- p.2 / Chapter 1.3 --- Separation and Purification of Chemical Ingredients --- p.2 / Chapter 1.3.1 --- Thin Layer Chromatography (TLC) --- p.3 / Chapter 1.3.2 --- Open Column Chromatography (OCC) --- p.4 / Chapter 1.4 --- Methods of Structural Identification --- p.4 / Chapter 1.4.1 --- Nuclear Magnetic Resonance (NMR) --- p.5 / Chapter 1.4.1.1 --- Proton NMR Spectroscopy (1H-NMR) --- p.5 / Chapter 1.4.1.2 --- Carbon-13 NMR Spectroscopy (13C NMR) --- p.5 / Chapter 1.4.1.3 --- Distortionless Enhancement by Polarization Transfer (DEPT) Experiment --- p.6 / Chapter 1.4.1.4 --- Two-dimensional Homonuclear Correlation Experiment --- p.6 / Chapter 1.4.1.5 --- Two-dimensional Heternuclear Chemical shift Correlation Experiment --- p.7 / Chapter 1.4.2 --- Mass Spectroscopy --- p.7 / Chapter 1.5 --- Literature Review --- p.8 / Chapter 1.5.1 --- Medical information on the genus Zanthoxylum --- p.8 / Chapter 1.5.2 --- Compounds found in the genus Zanthoxylum --- p.8 / Chapter 1.5.3 --- Compounds found in the Zanthoxylum acanthopodium --- p.9 / Chapter 1.5.4 --- Biological activities of the genus Zanthoxylum --- p.9 / Chapter 1.6 --- Research plan and Objectives of the present study --- p.16 / Chapter 1.7 --- References --- p.17 / Chapter Chapter 2: --- Materials and Methods --- p.20 / Chapter 2.1 --- General experimental procedures --- p.20 / Chapter 2.1.1 --- Solvents --- p.20 / Chapter 2.1.2 --- Chromatographic methods --- p.20 / Chapter 2.1.2.1 --- Normal phase chromatography --- p.20 / Chapter 2.1.2.2 --- Macro-reticular resinous adsorption chromatography --- p.20 / Chapter 2.1.3.3 --- Normal phase preparative thin layer chromatography --- p.21 / Chapter 2.1.3.4 --- Thin layer chromatography --- p.21 / Chapter 2.1.3 --- Determination of physical data --- p.21 / Chapter 2.1.3.1 --- Melting point determination --- p.21 / Chapter 2.1.3.2 --- Optical Rotation (OR) --- p.21 / Chapter 2.1.3.3 --- Ultraviolet (UV) absorption spectra --- p.22 / Chapter 2.1.3.4 --- Infra-red (IR) absorption spectra --- p.22 / Chapter 2.1.3.5 --- Nuclear Magnetic Resonance spectra (NMR) --- p.22 / Chapter 2.1.3.6 --- Mass Spectra (MS) --- p.22 / Chapter Chapter 3: --- Results / Chapter 3.1 --- "Procurement, extraction and initial fractionation of dried leaves and stem bark of Zahthoxylum acanthopodium" --- p.23 / Chapter 3.2 --- Chromatographic separation of the hexane and ethyl acetate extract --- p.24 / Chapter 3.2.1 --- Column chromatographic separation of fraction HEA-E --- p.24 / Chapter 3.2.1.1 --- Characterization of β -sitosterol --- p.24 / Chapter 3.2.2 --- Column chromatographic separation of fraction HEA-F --- p.25 / Chapter 3.2.2.1 --- Characterization of β -amyrin --- p.25 / Chapter 3.2.2.2 --- Characterization of 1 - octacosanol --- p.26 / Chapter 3.2.2.3 --- Characterization of (-)-sesamin --- p.26 / Chapter 3.2.3 --- Column chromatographic separation of fraction HEA-G --- p.27 / Chapter 3.2.3.1 --- Characterization of methyl hexacosanoate --- p.27 / Chapter 3.2.3.2 --- Characterization of methyl pluviatilol --- p.28 / Chapter 3.2.4 --- Column chromatographic separation of fraction HEA-H --- p.28 / Chapter 3.2.4.1 --- Characterization of (+)-methyl piperitol --- p.29 / Chapter 3.2.4.2 --- Characterization of (-)-epieudesmin --- p.29 / Chapter 3.2.5 --- Column chromatographic separation of fraction HEA-K --- p.29 / Chapter 3.2.5.1 --- Characterization of (+)-syringaresinol --- p.30 / Chapter 3.2.6 --- Column chromatographic separation of fraction HEA-M --- p.30 / Chapter 3.2.6.1 --- Characterization of daucosterol 6'-stearate --- p.31 / Chapter 3.2.7 --- Column chromatographic separation of fraction HEA-P --- p.31 / Chapter 3.2.7.1 --- Characterization of β -sitosterol- β -D-glucoside --- p.31 / Chapter 3.3 --- Chromatographic separation of the n-butanol extract --- p.32 / Chapter 3.3.1 --- Column chromatographic separation of fraction Bu-I --- p.32 / Chapter 3.3.1.1 --- Characterization of collettiside III --- p.32 / Chapter 3.3.1.2 --- Characterization of gracilline --- p.33 / Chapter Chapter 4: --- Discussion --- p.35 / Chapter 4.1 --- Isolated compounds --- p.35 / Chapter 4.1.1 --- Sterols --- p.35 / Chapter 4.1.1.1 --- Identification of -sitosterol --- p.36 / Chapter 4.1.1.2 --- Identification of β -sitosterol- β -D-glucoside --- p.41 / Chapter 4.1.1.3 --- Identification of daucosterol 6'-stearate --- p.45 / Chapter 4.1.2 --- Saponins --- p.50 / Chapter 4.1.2.1 --- Steroid glycosides --- p.51 / Chapter 4.1.2.1.1 --- Identification of collettiside III --- p.51 / Chapter 4.1.2.1.2 --- Identification of gracilline --- p.55 / Chapter 4.1.3 --- Terpenoid --- p.60 / Chapter 4.1.3.1 --- Identification of β -amyrin --- p.61 / Chapter 4.1.4 --- Lignans --- p.66 / Chapter 4.1.4.1 --- Identification of (-)-sesamin --- p.68 / Chapter 4.1.4.2 --- Identification of (-)-epieudesmin --- p.69 / Chapter 4.1.4.3 --- Identification of (+)-methyl piperitol --- p.70 / Chapter 4.1.4.4 --- Identification of methyl pluviatilol --- p.71 / Chapter 4.1.4.5 --- Identification of (+)-syringaresinol --- p.72 / Chapter 4.1.5 --- Alkanol --- p.78 / Chapter 4.1.5.1 --- Identification of 1 -octacosanol --- p.78 / Chapter 4.1.5.2 --- Identification of methyl hexacosanoate --- p.79 / Chapter 4.2 --- Conclusion --- p.81 / Chapter 4.3 --- References --- p.83

Thesis (M. Sc.)--University of Hong Kong, 1957. / References: p.48-51. "The occurrence of triterpenes in the aquifoliaceae and ericacear of Hong Kong, by H.R. Arthur, C.M. Lee and C.N. Ma" in pocket on inside of back cover. Type-written copy.

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