At last, a thermal evaporation method that modifies the surface of ZnO nanorods and forms core shell structure is developed, which structure constitutes the photoelectrode for solar energy application. Single crystal ZnO nanorods are uniformly covered by wurtzite polycrystalline CdxZn1-x SySe1-y layer. The band gap of the shell can be systematically tuned from 2.5 to 1.7 eV by varying its composition, as suggested by the optical extinction measured of the samples. The type II band alignment between the ZnO core and the alloy shell enables effective photo-generated charge carrier separation, and the single crystalline ZnO nanorod array provides a direct electrical pathway for the photo-injected electron transport. The nanocable solar cells exhibited short-circuit current ∼0.2 mA/cm 2 and open-circuit voltages of 0.45 V when illuminated with 100 mW/cm 2 simulated AM 1.5 spectrum. / Green emission is observed from the ZnO nanorods synthesized by both methods, which is commonly attributed to the surface defect emission from the nanostructure. We modify surface of the nanorods with SiO 2 and investigate the relation between green emission and the surface defect. However, the surface passivation fails to reduce the green emission significantly, suggesting that surface defects of ZnO are not necessarily responsible for the green emission, but the interior structure quality of the ZnO nanorods decides the luminescence behavior. / In this study, a solution chemistry based method to grow aligned ZnO nanorod arrays on Zn foil is developed at first. Effects of various growth parameters, including the temperature, solution composition and the concentration of individual components on the morphology, structural quality, and properties of the ZnO nanorods are studied. The average diameter of the nanorods in the array can be tuned from ∼20 nm to ∼150 nm by systematically changing the growth conditions. Nanorods with larger diameters are found to be of better structural quality as compared to the smaller diametered ones, as suggested by the cathodoluminescence measurement. Following similar logic, a vapor transport deposition route on controllable fabricating of the ZnO nanorod arrays is investigated. The average diameter of the ZnO nanorods can be tuned from less than 40 nm to larger than submicron, by controlling the fabrication conditions. Larger-diametered nanorods that grow on higher temperature zone are found to possess higher band edge to defect emission ratio. / One dimensional (1D) ZnO nanostructure becomes a research focus in recent years. On the one hand, ZnO itself possesses structural, electrical and optical properties that make it useful for a diverse range of technological applications. On the other hand, semiconductor nanowire owns many advantages, such as superiority in electron transport and its high surface to volume ratio. Aligned ZnO 1D nanostructures on conducting substrates are of special interests, as they are easy to be integrated into devices, directly working as functional unit. / Jiao, Yang. / Adviser: Li Quan. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 107-109). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Jiao, Yang.

Ge(100) has atomic and electronic structures quite similar to those of Si(100). As a comparison, we have studied the oxidation of Ge(100) surface. Our comparison of the initial oxidation of Ge(100) with that of Si(100) by molecular oxygen shows that the precursor-mediate mechanism and direct adsorption mechanism are common to both systems. (Abstract shortened by UMI.) / It is often been argued that a direct [2+2] addition of unsaturated hydrocarbons to the Si-Si dimer is symmetry forbidden, according to the Woodward-Hoffmann rule. This view is now challenged by our calculations on the reaction path for a concerted [2+2] addition of C2H4 to a Si-Si dimer on Si(100), which identifies a barrier of only ∼0.1eV. Our analysis shows that this is due to the peculiar feature for a surface reaction, when the HOMO and LUMO bands cross the Fermi level of the substrate, as previously suggested by Hoffmann. It illustrates an important conceptual distinction between a gas phase and a surface reaction. / Many previous theoretical studies on the interaction between O2 and Si(100) have neglected the differences between triplet O2 (ground state) and singlet O2 (excited state), and are thus unable to explain the know experimental observations in surface scattering of O2. We demonstrate that in reality, triplet O2 can also react with Si(100). With our computation results on the potential energy curves of the adsorption of triplet O2 on Si(100) and the adsorption structures along these curves, we can explain the known experimental results. The proper adsorption pathway goes through a shallow physisorption potential well, a small transition state and reaches a molecular adsorption state. There are also some interesting interactions between the potential energy curves of the triplet O2 adsorption and singlet O2 adsorption. / This thesis addresses the basic physics and chemistry of some surface reactions by first-principles methods based on density functional theory. The reaction systems probed by this thesis include the cycloaddition of C2H4 on Si(100), and initial oxidation of Si(100), Ge(100) and Al(111) by molecular oxygen. They are all technologically important systems and yet simple enough for us to study them in details theoretically. Although they have been studied both experimentally and theoretically, our first principles calculations reveal new insights that are contrary to prevalent opinions. / Fan Xiaoli = 从头算法研究研究在硅100, 锗100 和铝111 表面上的反应 / 范晓丽. / "June 2005." / Adviser: Lau Woon-ming Leo. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3854. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Text in English; abstracts in English and Chinese. / School code: 1307. / Fan Xiaoli = Cong tou suan fa yan jiu yan jiu zai gui 100, zhe 100 he lü111 biao mian shang de fan ying / Fan Xiaoli.

Finally, we have systematically investigated the SAMs of four specially designed anthracene-based thiols. These molecules include 9-mercaptoanthracene (MA), (4-mercaptophenyl) (9-anthryl) acetylene (MPAA), (4-mercaptophenyl) (10-nitro-9-anthryl) acetylene (MPNAA), and (4-mercaptophenyl) (10-carboxyl-9-anthryl) acetylene (MPCAA) adsorbed on Au(111). For all SAMs, the parallel-displaced pi-pi stacking interactions and adsorbate-substrate interactions are dominant, which leads to a common wave-like row structure along the pi-pi interaction direction. Compared to MA, the phenyl-acetylene group of MPAA acts as space, which enhances the molecular flexibility and improves the long-range ordering. The repulsive dipole-dipole interactions of MPCAA cause a slight enlargement of the unit cell. For MPCAA, a structure similar to that of MPNAA is formed first. Then with an extended growth time, hydrogen bonding drives the pairing of adjacent inter-row molecules in the expenses of compromising intea-row parallel-displaced pi-pi interaction. / Fourth, we studied the growth of CF3 CH2SH on Au(111). We found that the adsorbed molecules mainly form low coverage phases even after a long time growth in solution. This is attributed to the strong dipole-dipole repulsion between the molecules. However, due to the special short molecular geometry, the molecules can pack with a denser packing arrangement in comparison to the long-chain fluorinated thiols. A "liquid phase" is present in all the samples studied, which solidifies quickly at elevated temperatures. Annealing causes both the growth of stable phases and desorption of weakly adsorbed molecules. Six different stripe phases with the configuration of p x 3 and p x 2a are observed on the surface. The inter-molecular interactions are either van der Waals in nature or the Columbic attraction between the slightly negatively charged F atoms and the slightly positively charged H atoms of the CH 2 group. / Second, we have observed several dash-line structures on HOPG with STM. We suggest that the structures are formed by the gliding of some top surface layers of carbon atoms. The arrest of the gliding action causes the formation of a ridge of carbon atoms and the relaxation of the ridge at room temperature leads to the formation of amorphous carbon clusters queuing along the ridge. As such, the dash-line structures are formed. They are defect structures of HOPG. / Several adsorption systems have been studied by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) in this thesis. / The first system is Fe deposited on 3 x 3 -Al on Si(111). We found by STM that at a low coverage of less than 0.1ML and room temperature; most Fe atoms are incorporated to the 3 x 3 -Al adatom lattice. When the Fe coverage increases further, clustering of Fe atoms into three-dimensional islands occurs. These clusters draw neighboring silicon surface or sub-surface atoms and the formation of Fe-Si bonds is evident. Samples with Fe deposited at or above 400°C show Fe-Si with the CsCl crystalline structure and a top surface lattice of 2 x 2 Si (111) in nature. The crystalline island has a triangular shape and a preferred location along the step edges of the Si(111) surface. / Third, STM has been used successfully in determining the molecular morphology of some novel dendrimers. The morphology of dispersed individual molecule can be identified. In this study, we found that AFM is not applicable because of considerable tip-molecule interactions which distort the morphology of the probed molecule. / Xi Luan = SPM对表面吸附分子的研究 / 席峦. / "June 2005." / Adviser: Lau Woon Ming Leo. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0491. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 109-117). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Text in English; abstracts in English and Chinese. / School code: 1307. / Xi Luan = SPM dui biao mian xi fu fen zi de yan jiu / Xi Luan.

As for the 3D deformable surface recovery, the key challenge arises from the difficulty in estimating a large number of 3D shape parameters from noisy observations. In this thesis, 3D deformable surface tracking is formulated into an unconstrained quadratic problem that can be solved very efficiently by resolving a set of sparse linear equations. Furthermore, the robust progressive finite Newton method developed for nonrigid surface detection is employed to handle the large outliers. / For the appearance-based method, a deformable Lucas-Kanade algorithm is proposed which triangulates the template image into small patches and constrains the deformation through the second order derivatives of the mesh vertices. It is formulated into a sparse regularized least squares problem which is able to reduce the computational cost and the memory requirement. The inverse compositional algorithm is applied to efficiently solve the optimization problem. Furthermore, we present a fusion approach to take advantage of both the appearance information and the local features. / In addition to the methodologies studied and evaluated in computer vision, this thesis also investigates the nonrigid surface recovery in some real-world multimedia applications, such as Near-duplicate image retrieval and detection. In contrast to conventional approaches, the presented technique can recover an explicit mapping between two near-duplicate images with a few deformation parameters and find out the correct correspondences from noisy data effectively. To make the proposed technique applicable to large-scale applications, an effective multilevel ranking scheme is presented that filters out the irrelevant results in a coarse-to-fine manner. To overcome the extremely small training size challenge, a semi-supervised learning method is employed to improve the performance using unlabeled data. Extensive evaluations show that the presented method is clearly effective than conventional approaches. / Recovering deformable surfaces is an interesting and beneficial research problem for computer vision and image analysis. An effective deformable surface recovery technique can be applied in a variety of applications for surface reconstruction, digital entertainment, medical imaging and Augmented Reality. While considerable research efforts have been devoted to deformable surface modeling and fitting, there are only few schemes available to tackle the deformable surface recovery problem efficiently. This thesis proposes a set of methods to effectively solve the 2D nonrigid shape recovery and 3D deformable surface tracking based on a robust progressive optimization scheme. The presented techniques are also applied to a variety of real-world applications. / To tackle the 2D nonrigid shape recovery problem, this thesis first presents a novel progressive finite Newton optimization scheme, which is based on the local feature correspondences. The key of this approach is to formulate the nonrigid shape recovery as an unconstrained quadratic optimization problem which has a closed-form solution for a given set of observations. / Without resorting to an explicit deformable mesh model, the nonrigid surface detection can be treated as a generic regression problem. A novel velocity coherence constraint is imposed on the deformable shape model to regularize the ill-posed optimization problem. To handle the large outliers, a progressive optimization scheme is employed. / Zhu, Jianke. / Adviser: Michael R. Lyu. / Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: . / Thesis submitted in: December 2008. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 161-175). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Styrene (C2H3-C6H5) is expected to have a more complex reaction process due to active reaction sites located in both vinyl group and phenyl group. Our exploration indicates that the adsorption products are coverage dependent. At low coverage, both vinyl group and phenyl group are possible to take part in the adsorption process. A new AsymT adsorption state covered two adjacent Si dimers is identified through two [4+2] cycloaddition. At high coverage, only vinyl group can interact with Si dimer to form cis and trans stereoisomers with different thermal energies and kinetic reaction barriers. STM images and vibrational frequencies are also explored to further support the experimental observations. / The adsorption of unsaturated organic molecules on reconstructed Si(100) surface is widely applied in the modification and functionalization of silicon surface to design new semiconductor materials. The present project is devoted to explore the adsorption mechanisms and the related properties of adsorption species for unsaturated organic molecules: acetylene (C2H 2), ethylene (C2H4), vinyl bromide (C2H 3Br) and styrene (C8H8) by quantum chemical calculation, based on density functional theory (DFT) method with pseudopotentials and plane wave basis set. / The investigation of vinyl bromide (C2H3Br) chemisorption on Si(100) resolves the conflicting conclusions between previous experimental and theoretical studies. The orientation of the vinyl bromide molecule relative to the titled silicon dimer is found to be an important factor for both the stability and reactivity of the precursor state. A new precursor pi-complex is identified, which is metastable and trapped by barriers around 0.1eV. Comparisons between theoretical and experimental vibrational frequencies support the conclusion that such a pi-complex is present on the surface at very low temperature. Careful analysis on the electronic structure also demonstrates that it is indeed a pi-complex rather than a diradical as previously suggested. Reaction mechanisms at higher vinyl bromide coverage are also modeled to explain the decrease in activation barrier observed in experiments. / The reaction processes for acetylene (C2H2) and ethylene (C2H4) chemisorption on the surface silicon dimer and the sub-layer silicon atoms are compared. Acetylene can undergo a new type of cycloaddition on sub-layer Si atoms (called sub-di-sigma) with no barrier, which is identified by ab initio Molecular Dynamics. The related properties including vibrational frequencies and STM images are calculated and found to be similar with those of the end-bridge adsorption structure. The identification of such a sub-di-sigma adsorption structure explains the discrepancy between STM experiments and theoretical calculations. In addition, the analysis of calculated vibrational frequencies, simulated STM images and the reaction barriers for di-sigma and end-bridge structures indicate that inter-dimer reaction for C2H4 is possible. / Zhang, Qiuji. / Adviser: Zhi Feng Liu. / Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: . / Thesis submitted in: October 2008. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 86-87). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Tse, Wang Hung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 75-77). / Abstract also in Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- On bounded interval with n jumps in inhibitor diffusivity --- p.3 / Chapter 2.1 --- Introduction --- p.3 / Chapter 2.2 --- Preliminaries --- p.5 / Chapter 2.3 --- Review of previous results in the two segment case: interior spike and spike near the jump discontinuity of the diffusion coefficient --- p.7 / Chapter 2.4 --- The construction and analysis of spiky steady-state solutions --- p.9 / Chapter 2.5 --- Stability Analysis --- p.10 / Chapter 2.6 --- Spikes near the jump discontinuity xb of the inhibitor diffusivity --- p.11 / Chapter 2.7 --- Stability Analysis II: Small Eigenvalues of the Spike near the Jump --- p.16 / Chapter 2.8 --- Existence of interior spikes for N segments --- p.20 / Chapter 2.9 --- Existence of a spike near a jump for N segments --- p.24 / Chapter 2.10 --- Appendix: The Green´ةs function for three segments --- p.25 / Chapter 3 --- On a compact Riemann surface without boundary --- p.30 / Chapter 3.1 --- Introduction --- p.30 / Chapter 3.2 --- Some Preliminaries --- p.35 / Chapter 3.3 --- Existence --- p.43 / Chapter 3.4 --- Refinement of Approximate Solution --- p.50 / Chapter 3.5 --- Stability --- p.52 / Chapter 3.6 --- Appendix I: Expansion of the Laplace-Beltrami Operator --- p.67 / Chapter 3.7 --- Appendix II: Some Technical Calculations --- p.73

Chan, Kin Wai. / "September 2010." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 103-106). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.8 / Chapter 2 --- Background Knowledge --- p.13 / Chapter 2.1 --- Results from Riemann Surface Theory and Quasicon- formal Mappings --- p.13 / Chapter 2.1.1 --- Riemann Surfaces and the Uniformization The- orem --- p.13 / Chapter 2.1.2 --- Fuchsian Groups --- p.15 / Chapter 2.1.3 --- Quasiconformal Mappings and the Beltrami Equation --- p.17 / Chapter 2.1.4 --- Holomorphic Quadratic Differentials --- p.20 / Chapter 2.1.5 --- Nodal Riemann Surfaces --- p.21 / Chapter 2.2 --- Teichmuller Theory --- p.24 / Chapter 2.2.1 --- Teichmiiller Spaces --- p.24 / Chapter 2.2.2 --- Teichmuller's Distance --- p.26 / Chapter 2.2.3 --- The Bers Embedding --- p.26 / Chapter 2.2.4 --- Teichmuller Modular Groups and Moduli Spaces of Riemann Surfaces --- p.27 / Chapter 2.2.5 --- Infinitesimal Theory of Teichmiiller Spaces --- p.28 / Chapter 2.2.6 --- Boundary of Moduli Spaces of Riemann Sur- faces --- p.29 / Chapter 2.3 --- Schwarz-Yau Lemma --- p.30 / Chapter 3 --- Classical Canonical Metrics on the Teichnmuller Spaces and the Moduli Spaces of Riemann Surfaces --- p.31 / Chapter 3.1 --- Finsler Metrics and Bergman Metric --- p.31 / Chapter 3.1.1 --- Definitions and Properties of the Metrics --- p.32 / Chapter 3.1.2 --- Equivalences of the Metrics --- p.33 / Chapter 3.2 --- Weil-Petersson Metric --- p.36 / Chapter 3.2.1 --- Definition and Properties of the Weil-Petersson Metric --- p.36 / Chapter 3.2.2 --- Results about Harmonic Lifts --- p.37 / Chapter 3.2.3 --- Curvature Formula for the Weil-Petersson Met- ric --- p.41 / Chapter 4 --- Kahler Metrics on the Teichmiiller Spaces and the Moduli Spaces of Riemann Surfaces --- p.42 / Chapter 4.1 --- McMullen Metric --- p.42 / Chapter 4.1.1 --- Definition of the McMullen Metric --- p.42 / Chapter 4.1.2 --- Properties of the McMullen Metric --- p.43 / Chapter 4.1.3 --- Equivalence of the McMullen Metric and the Teichmuller Metric --- p.45 / Chapter 4.2 --- Kahler-Einstein Metric --- p.50 / Chapter 4.2.1 --- Existence of the Kahler-Einstein Metric --- p.50 / Chapter 4.2.2 --- A Conjecture of Yau --- p.50 / Chapter 4.3 --- Ricci Metric --- p.51 / Chapter 4.3.1 --- Definition of the Ricci Metric --- p.51 / Chapter 4.3.2 --- Curvature Formula of the Ricci Metric --- p.53 / Chapter 4.4 --- The Asymptotic Behavior of the Ricci Metric --- p.61 / Chapter 4.4.1 --- Estimates on the Asymptotics of the Ricci Metric --- p.61 / Chapter 4.4.2 --- Estimates on the Curvature of the Ricci Metric --- p.83 / Chapter 4.5 --- Perturbed Ricci Metric --- p.92 / Chapter 4.5.1 --- Definition and the Curvature Formula of the Perturbed Ricci Metric --- p.92 / Chapter 4.5.2 --- Estimates on the Curvature of the Perturbed Ricci Metric --- p.93 / Chapter 4.5.3 --- Equivalence of the Perturbed Ricci Metric and the Ricci Metric --- p.96 / Chapter 5 --- Equivalence of the Kahler Metrics on the Teichmuller Spaces and the Moduli Spaces of Riemann Surfaces --- p.98 / Chapter 5.1 --- Equivalence of the Ricci Metric and the Kahler-Einstein Metric --- p.98 / Chapter 5.2 --- Equivalence of the Ricci Metric and the McMullen Metric --- p.99 / Bibliography --- p.103

Gong, Xiangjun = 新型全內反射顯微鏡的搭建及其在膠體研究中的應用 / 龔湘君. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Abstracts in English and Chinese. / Gong, Xiangjun = Xin xing quan nei fan she xian wei jing de da jian ji qi zai jiao ti yan jiu zhong de ying yong / Gong Xiangjun. / Abstract (Chinese) --- p.i / Abstract --- p.iii / Contents --- p.v / Acknowledgement --- p.vii / Chapter Chapter 1 --- Introduction to Total Internal Reflection Microscopy (TIRM) / Chapter 1.1 --- History of TIRM --- p.1 / Chapter 1.2 --- Instrumentation --- p.1 / Chapter 1.2.1 --- Apparatus --- p.1 / Chapter 1.2.2 --- Optical Tweezer --- p.3 / Chapter 1.3 --- The principle of the technique --- p.5 / Chapter 1.3.1 --- Total Internal Reflection --- p.5 / Chapter 1.3.2 --- Details on Scattering of the Evanescent Wave --- p.7 / Chapter 1.3.3 --- Data analysis --- p.14 / Chapter 1.3.4 --- A typical potential energy profile --- p.17 / Chapter 1.4 --- Noise Analysis and Removal Method --- p.19 / Chapter 1.4.1 --- Noise analysis --- p.19 / Chapter 1.4.2 --- Noise removal: low-pass filtering --- p.22 / Chapter 1.5 --- Other techniques on force measurement --- p.25 / Chapter 1.6 --- References --- p.27 / Chapter Chapter 2 --- Experiments on TIRM Calibration / Chapter 2.1 --- Introduction --- p.30 / Chapter 2.2 --- Pre-Experimental Section --- p.30 / Chapter 2.2.1 --- Glass Surface Preparation Methods --- p.30 / Chapter 2.2.2 --- Experimental Setup --- p.33 / Chapter 2.3 --- Calibration Results and Discussion --- p.36 / Chapter 2.4 --- Conclusions --- p.42 / Chapter 2.5 --- References --- p.43 / Chapter Chapter 3 --- TIRM investigation on polymer-induced collodial interactions / Chapter 3.1 --- Introduction to polymer-induced forces --- p.45 / Chapter 3.1.1 --- Non-absorbing case - depletion force --- p.46 / Chapter 3.1.2 --- Attached polymer layers --- p.49 / Chapter 3.2 --- Applications of TIRM in polymer-mediated colloidal interactions --- p.54 / Chapter 3.2.1 --- Measurements on depletion force --- p.54 / Chapter 3.2.2 --- Measurements on Steric Forces --- p.56 / Chapter 3.3 --- Direct measurement of thermosensitive Poly(N-isopropylacrylamide)-mediated colloidal interactions with TIRM --- p.56 / Chapter 3.3.1 --- Introduction --- p.56 / Chapter 3.3.2 --- Experimental Section --- p.57 / Chapter 3.3.3 --- Results and Discussion --- p.60 / Chapter 3.3.4 --- Conclusions --- p.73 / Chapter 3.4 --- References --- p.74 / Publication List --- p.77

An experimental study of pure iron foil exposed to a hot, dense hydrogen and argon gas mixture in a ballistic compressor yielded evidence of structural and compositional changes of the metal due to the presence of the hydrogen gas. Three iron foils have been compared, one of unexposed pure iron, another of pure iron exposed to a mixture of hydrogen and argon gas, and the third of pure iron exposed to argon alone. Exposure to these high temperature, high pressure gases took place in a ballistic compressor. Line formations were found on the surface of the iron foil exposed to both hydrogen and argon. These appeared as 'V'- or 'W'-shaped configurations, giving the appearance of a serrated edge. Such lines were not found for the other two iron foils. Characteristic peaks of energy dispersive x-ray spectra yield different surface concentrations of oxygen when each iron foil sample is compared. This concentration is much less for iron foil exposed to both hydrogen and argon gases than for the other two samples. Also a larger carbon peak was found for the former sample, when compared to the latter two. A shift in the 200 x-ray diffraction peak by one degree 29 was observed for the sample exposed to hydrogen and argon, and a 'triple' peak was observed for the 310 plane for the same iron sample.

Ce travail présente la conception, la fabrication et le test d’une unité de préparation d’échantillons utilisant une approche originale combinant les microfluidiques digitale et continue. L'avantage du préconditionnement ‘numérique’ est d’éviter l’introduction d'un réseau complexe de micro-vannes pour manipuler les échantillons, tandis que le format ‘continu’ en entrée et sortie de l’unité permet de coupler facilement ce dispositif avec des composants microfluidiques situés en amont et en aval. Nous avons travaillé sur deux procédés de fabrication. Le premier comprend un tricouche PSP (Pyrex-Silicium-Pyrex) pour lequel les interfaces liquide-solide sont de nature hydrophobe. Un procédé original de collage thermoplastique a été optimisé qui est suffisamment générique pour être utilisé dans d’autres procédés MEMS. Cependant, les résultats des caractérisations ont montré que bon nombre des échantillons ne pouvaient pas être manipulés. Pour résoudre ce problème, nous avons développé un procédé bicouche PS (Pyrex-silicium) où les interfaces liquide-solide sont de nature superhydrophobe suite à une nanotexturation du silicium par traitement chimique. Grâce à la faible hystérésis, la résistance de friction et la pollution biologique sont largement réduites ce qui permet la manipulation de liquides complexes. Cette technologie a été employée pour fabriquer une unité microfluidique dédiée à de la préparation d’échantillons issus de bioprocédés à base de levures. Ces échantillons préparés sont ensuite analysés soit par une méthode immuno-enzymatique (ELISA) soit par une analyse par spectrométrie de masse précédée par une étape de séparation par électrophorèse capillaire. / This work presents the concept, fabrication technology and characterization of a sample preparation unit using an original approach coupling channel-based continuous and electrowetting-on-dielectric (EWOD)-based digital microfluidics. The major advantage of ‘digital’ is the accurate control of multiple reagents without the need of a complex network of microvalves, while unprocessed and reprocessed ‘continuous’ format is ideal for coupling with upstream and downstream microfluidic devices. We have developed two generations. In our first work, a three layers PSP (Pyrex-Silicon-Pyrex) configuration with hydrophobic liquid-solid interfaces was employed. An original adhesive wafer bonding technique has been optimized that is sufficiently generic to be used in diverse MEMS processes. However, the preliminary characterization results have shown that most real samples used in bioprocessing could not be handled by this first prototype. To address this issue, we have developed a bilayer PS (Pyrex-Silicon) configuration with superhydrophobic liquid-solid interfaces made by chemical nanotexturation of silicon. Thanks to the low contact angle hysteresis of this superhydrophobic surface, the friction resistance and bio-adsorption on the surface were largely reduced allowing transport of real complex liquids. Finally, this prototype has been successfully used for preconditioning samples taken from a yeast bio-reactor and then delivered to analytical modules either an enzyme-linked immunosorbent assay (ELISA) or a capillary electrophoresis (CE) device coupled with a mass spectrometry (MS).