Progress in chemomechanical functionalization was made by investigating the binding of molecules and surface coverage on the silicon surface, demonstrating functionalization of silicon with gases by chemomechanical means, analyzing atomic force microscopy probe tip wear in atomic force microscopy (AFM) chemomechanical nanografting, combining chemomechanical functionalization and nanografting to pattern silicon with an atomic force microscope, and extending chemomechanical nanografting to silicon dioxide. Molecular mechanics of alkenes and alkynes bound to Si(001)-2x1 as a model of chemomechanically functionalized surfaces indicated that complete coverage is energetically favorable and becomes more favorable for longer chain species. Scribing a silicon surface in the presence of ethylene and acetylene demonstrated chemomechanical functionalization with gaseous reagents, which simplifies sample cleanup and adds a range of reagents to those possible for chemomechanical functionalization. Thermal desorption spectroscopy was performed on chemomechanically functionalized samples and demonstrated the similarity in binding of molecules to the scribed silicon surface and to the common Si(001)-2x1 and Si(111)-7x7 surfaces. The wearing of atomic force microscope probe tips during chemomechanical functionalization was investigated by correlating change over time and force with widths of created lines to illustrate the detrimental effect of tip wear on mechanically-driven nanopatterning methods. In order to have a starting surface more stable than hydrogen-terminated silicon, silicon reacted with 1-octene was used as a starting surface for AFM chemomechanical functionalization, producing chemomechanical nanografting. Chemomechanical nanografting was then demonstrated on silicon dioxide using silane molecules; the initial passivating layer reduced the tip friction on the surface to allow only partial nanografting of the silane molecules. These studies broadened the scope and understanding of chemomechanical functionalization and nanografting.

Obwohl wir sie oft nicht bewusst wahrnehmen, sind Nanopartikel heutzutage in den meisten Bereichen unseres Alltags präsent, unter anderem in Lebensmitteln und ihren Verpackungen, Medizin, Medikamenten, Kosmetik, Pigmenten und in elektronischen Geräten wie Computermonitoren. Ein Großteil dieser Partikel weist, beabsichtigt oder unbeabsichtigt, eine Kern-Schale Morphologie auf. Einfachheitshalber wird diese Morphologie eines Kern-Schale-Nanopartikels (CSNP) oft als ideal angenommen, d.h. als ein sphärischer Kern, der komplett von einer Schale homogener Dicke bedeckt ist, mit einer scharfen Grenzfläche zwischen Kern- und Schalenmaterial. Außerdem wird vielfach auch davon ausgegangen, alle Partikel der Probe hätten gleiche Schalendicken. Tatsächlich weichen die meisten realen CSNPs in verschiedenster Weise von diesem Idealmodell ab, mit oft drastischen Auswirkungen darauf, wie gut sie ihre Aufgabe in einer bestimmten Anwendung erfüllen. Das Thema dieser kumulativen Doktorarbeit ist die exakte Charakterisierung der wirklichen Morphologie von CSNPs mit modernen Röntgen-basierten Methoden, konkret Röntgen-Photoelektronen-Spektroskopie (XPS) und Raster-Transmissions-Röntgen-Mikroskopie (STXM). Der Fokus liegt insbesondere auf CSNPs, die von einer idealen Kern-Schale-Morphologie abweichen. Aufgrund der enormen Vielfalt an CSNPs, die sich in Material, Zusammensetzung und Form unterscheiden, kann eine Messmethode nicht völlig unverändert von einer Probe auf eine andere übertragen werden. Nichtsdestotrotz, da die als Teil dieser Doktorarbeit präsentierten Artikel eine deutlich ausführlichere Beschreibung der Experimente enthalten als vergleichbare Publikationen, stellen sie eine wichtige Anleitung für andere Wissenschaftler dafür dar, wie aussagekräftige Informationen über CSNPs durch Oberflächenanalytik erhalten werden können. / Even though we often do not knowingly recognize them, nanoparticles are present these days in most areas of our daily life, including food and its packaging, medicine, pharmaceuticals, cosmetics, pigments as well as electronic products, such as computer screens. The majority of these particles exhibits a core-shell morphology either intendedly or unintendedly. For the purpose of practicability, this core-shell nanoparticle (CSNP) morphology is often assumed to be ideal, namely a spherical core fully encapsulated by a shell of homogeneous thickness with a sharp interface between core and shell material. It is furthermore widely presumed that all nanoparticles in the sample possess the same shell thickness. As a matter of fact, most real CSNPs deviate in several ways from this ideal model with quite often severe impact on how efficiently they perform in a specific application. The topic of this cumulative PhD thesis is the accurate characterization of the actual morphology of CSNPs by advanced X-ray analytical techniques, namely X-ray photoelectron spectroscopy (XPS) and scanning transmission X-ray microscopy (STXM). A special focus is on CSNPs which deviate from an ideal core-shell morphology. Due to the vast diversity of nanoparticles differing in material, composition and shape, a measurement procedure cannot unalteredly be transferred from one sample to another. Nevertheless, because the articles in this thesis present a greater depth of reporting on the experiments than comparable publications, they constitute an important guidance for other scientists on how to obtain meaningful information about CSNPs from surface analysis.

No description available.

<p>Surface preparation and its exposure to different processing conditions is a key step in heterogeneous integration of electronics, photonics, fluidics and/or mechanical components for More-than-Moore applications. Therefore, it is critical to understand how various processing and environmental conditions affect the surface properties of bonding substrates. In this thesis, the effects of oxygen reactive-ion etching (O₂ RIE) plasma followed by storage in ambient and 98% relative humidity on some key surface properties such as roughness, water contact angle, hardness, and the elemental and compositional states of three materials – silicon (Si), silicon dioxide (SiO₂) and glass – are investigated to analyze their influence on bondability. Lower O₂ RIE plasma activation times cause low surface roughness, high surface reactivity and high hydrophilicity of Si, SiO₂ and glass. The decrease of hardness of Si and SiO₂ with increased activation time is attributed to higher surface roughness and formation of amorphous layers of Si. While contact angle and surface roughness results show correlation with bondability, the role of hardness on bondability requires further investigation. The high-resolution X-ray Photoelectron Spectroscopy (XPS) spectra of O₂ RIE treated Si, SiO₂ and glass showed the presence of Si(-O)₂ resulting in highly reactive surfaces. The high surface reactivity of Si, SiO₂ and glass obtained from oxygen plasma activation at lower activation times can result in better bondability. Also, the ambient humidity-induced Si(-OH)_x plays an important role in the hydrophilic wafer bonding of Si and SiO₂ which may require a low temperature heating.</p> / Master of Applied Science (MASc)

<p>The aim of this thesis is to interconnect human tactile perception with various physical properties of materials. Tactile perception necessitates contact and relative motion between the skin and the surfaces of interest. This implies that properties such as friction and surface roughness ought to be important physical properties for tactile sensing. In this work, a method to measure friction between human fingers and surfaces is presented. This method is believed to best represent friction in tactile perception.</p><p>This study is focused on the tactile perception of printing papers. However, the methodology of finger friction measurements, as well as the methodology to link physical properties with human perception data, can be applied to almost whichever material or surfaces.</p><p> </p><p>This thesis is based on three articles.</p><p> </p><p>In Article I, one participant performed finger friction measurements, using a piezoelectric force sensor, on 21 printing papers of different paper grades and grammage (weight of the papers). Friction coefficients were calculated as the ratio of the frictional force and the normal force, shown to have a linear relationship. The values were recorded while stroking the index finger over the surface. The results show that measurements with the device can be used to discriminate a set of similar surfaces in terms of finger friction. When comparing the friction coefficients, the papers group according to paper surface treatment and an emerging trend is that the rougher (uncoated) papers have a lower friction coefficient than the smoother (coated) papers. In the latter case, this is interpreted in terms of a larger contact between the finger and paper surface.</p><p> </p><p>In addition, a decrease in friction coefficient is noted for all papers on repeated stroking, where the coated papers display a larger decrease. XPS (X-ray Photoelectron Spectroscopy) reveals that skin lipids are transferred from the finger to the paper surface, acting as a lubricant and hence decrease friction. Nevertheless, there is evidence that mechanical changes of the surface cannot be completely ruled out.</p><p> </p><p>The reproducibility of the finger friction measurements is elaborated in Article II, by using many participants on a selection of eight printing papers out of the 21. The trends in friction are the same; once again, the coated papers display the highest friction. There are notably large variations in the exact value of the friction coefficient, which are tentatively attributed to different skin hydration and stroking modes.</p><p> </p><p>These same participants also took part in a tactile study of perceived paper coarseness (“strävhet” in Swedish). The results reveal that the participants can distinguish a set of printing papers in terms of perceived coarseness. Not unexpectedly, surface roughness appears to be an important property related to perceived coarseness, where group data display that perceived coarseness increases with increasing surface roughness. Interestingly, friction also appears to be a discriminatory property for some subjects. A few participants showed opposite trends, which is evidence for that what is considered coarse is subjective and that different participants “weigh” the importance of the properties differently. This is a good example of a challenge when measuring one-dimensional perceptions in psychophysics.</p><p> </p><p>In Article III, a multidimensional approach was used to explore the tactile perception of printing papers. To do this, the participants scaled similarity among all possible pairs of the papers, and this similarity data are best presented by a three-dimensional space solution. This means that there are three underlying dimensions or properties that the participants use to discriminate the surface feel. Also, there is a distinct perceptual difference between the rougher (uncoated) and smoother (coated) papers. The surface roughness appears to be the dominant physical property when discriminating between a real rough paper and a smooth paper, whereas friction, thermal conductivity and grammage are more important when discriminating among the smooth coated papers.</p>

<p>In this thesis we have performed core-electron spectroscopy studies of gas phase molecular systems starting with smaller diatomic, continuing with triatomic and extending our research to more complex polyatomic ones. We can subdivide the results presented here into two categories: the first one focusing on electronic fine structure and effect of the chemical bonds on molecular core-levels and the other one dealing with nuclear dynamics induced by creation of a core hole. In our research we have mostly used synchrotron radiation based techniques such as X-ray Photoelectron (XPS), X-ray Absorption (XAS), normal and Resonant Auger (AES and RAS, respectively) and Energy-Selected Auger Electron PhotoIon COincidence (ES-AEPICO) spectroscopies.</p><p>We have demonstrated that resonant Auger spectroscopy can be used to aid interpretation of the features observed in XAS for Rydberg structures in the case of Cl₂ and C1s⁻¹π*¹ states of allene molecules. The combined use of high-resolution spectroscopy with <i>ab initio</i> calculations can help the interpretation of strongly overlapped spectral features and disentangle their complex profiles. This approach enabled us to determine the differences in the lifetimes for core-hole 2p sublevels of Cl₂ which are caused by the presence of the chemical bond. We have shown that contribution in terms of the Mulliken population of valence molecular orbitals is a determining factor for resonant enhancement of different final states and fragmentation patterns reached after resonant Auger decays in N₂O.</p><p>We have also performed a systematic study of the dependence of the C1s resonant Auger kinetic energies on the presence of different substituents in CH₃X compounds. For the first time we have studied possible isomerization reaction induced by core excitation of acetylacetone. We could observe a new spectral feature in the resonant Auger decay spectra which we interpreted as a signature of core-excitation-induced keto-enol tautomerism.</p>

Thin-film transistors (TFTs) are primarily used as a switching element in liquid crystal displays. Currently, amorphous silicon is the dominant TFT technology for displays, but higher performance TFTs will become necessary to enable ultra-definition resolution high-frequency large-area displays. Amorphous zinc tin oxide (ZTO) TFTs were fabricated by RF magnetron sputter deposition. In this study, the effect of both deposition and post annealing conditions have been evaluated in regards to film structure, composition, surface contamination, and device performance. Both the variation of oxygen partial pressure during deposition and the temperature of the post-deposition annealing were found to have a significant impact on TFT properties. X-ray diffraction data indicated that the ZTO films remain amorphous even after annealing to 600° C. Rutherford backscattering spectrometry indicated that the Zn:Sn ratio of the films was ~1.7:1 which is slightly tin rich compared to the sputter target composition. X-ray photoelectron spectroscopy data indicated that the films had significant surface contamination and that the Zn:Sn ratios changed depending on sample annealing conditions. Electrical characterization of ZTO films using TFT test structures indicated that mobilities as high as 17 cm² V⁻¹ s⁻¹ could be obtained for depletion mode devices. It was determined that the electrical properties of ZTO films can be precisely controlled by varying the deposition conditions and annealing temperature. It was found that the ZTO electrical properties could be controlled where insulating, semiconducting and conducting films could be prepared. This precise control of electrical properties allowed us to incorporate sputter deposited ZTO films into resistive random access memory (RRAM) devices. RRAM are two terminal nonvolatile data memory devices that are very promising for the replacement of silicon-based Flash. These devices exhibited resistive switching between high-resistance states to low-resistance states and low-resistance states to high-resistance states depending on polarity of applied voltages and current compliance settings. The device switching was fundamentally related to the defect states and material properties of metal and insulator layers, and their interfaces in the metalinsulator-metal (MIM) structure. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Jan. 6, 2012 - Jan. 6, 2013

Die vorliegende Dissertation beschreibt die Erarbeitung anwendbarer Methoden zum Aufbau Oberflächenplasmonenresonanz (SPR)-basierter DNA-Mikroarrays. Es werden die Beziehungen zwischen allen Teilschritten der Entwicklung eines DNA-Biosensors aufgezeigt. Die Sondendichte auf der Sensoroberfläche ist entscheidend für die Leistungsfähigkeit eines DNA-Chips. In dieser Arbeit werden thiolmodifizierte Sonden und solche mit Phosphorothioatgruppen verwendet und verglichen. Der Aufbau selbstorganisierender Monoschichten, bestehend aus Mercaptoalkoholen und thiolmodifizierten DNA-Einzelsträngen, wird mittels Röntgenphotoelektronenspektroskopie untersucht. Es werden bis zu 180 Spots auf einem SPR-Chip aufgetragen. Eine weitere Erhöhung der Anzahl an Sondenorten pro Chip wird mit einer hydrophil/hydrophoben Strukturierung der Arrayoberfläche erreicht. Dies erfolgt durch das Mikrokontaktdrucken mit Alkanthiolen. Die selektiven Hybridisierungen der Produkte der Polymerase-Kettenreaktion (PCR) werden bei SPR-Messungen auf DNA-Mikroarrays detektiert. Eine schnelle markierungsfreie Echtzeitanalyse wird bei Hybridisierungen im mikrofluidischen Kanal innerhalb weniger Minuten erzielt. Die Anwendbarkeit dieser Methoden wurde anhand der Mutationsanalyse der Fusionsgene AML1-ETO und CBFB-MYH11 bei der akuten myeloischen Leukämie bestätigt. Die Hybridisierungseffizienz auf DNA-Mikroarrays hängt stark von der Sodensequenz ab. SPR-Experimente zeigen, dass die Ausbildung der Haarnadelstrukturen die Ursache dafür ist. Ein Computerprogramm (EGNAS) auf Grundlage eines neu entwickelten Nucleobasen-Sequenzentwurf-Algorithmus, ermöglicht die Generierung vollständiger Sequenzsätze. Die Intra- und Interstrangeigenschaften dieser Sequenzen können kontrolliert werden, um Haarnadelstrukturen und Kreuzhybridisierungen zu vermeiden. Dadurch können optimierte Sequenzen für Anwendungen auf DNA-Chips oder in der DNA-Nanobiotechnologie entworfen werden.

Metal oxides are of immense technological importance. Their wide variety of structural and electronic characteristics leads to a flexibility unrivalled by other groups of materials. However, there is still much debate about the fundamental properties of some of the most widely used oxides, including TiO₂ and In₂O₃. This work presents high quality, in-depth characterisation of these two oxides in pure and doped form, including soft and hard X-ray photoelectron spectroscopy and X-ray diffraction. Bulk samples as well as thin film samples were prepared analysed. For the preparation of thin films a high quality sol-gel dip-coating method was developed, which resulted in epitaxial films. In more detail the organisation of the thesis is as follows: Chapter 1 provides an introduction to key ideas related to metal oxides and presents the metal oxides investigated in this thesis, In₂O₃, Ga₂O₃, Tl₂O₃, TiO₂, and SnO₂. Chapter 2 presents background information and Chapter 3 gives the practical details of the experimental techniques employed. Chapters 4 presents reciprocal space maps of MBE-grown In₂O₃ thin films and nanorods on YSZ substrates. Chapters 5 and 6 investigate the doping of In₂O₃ bulk samples with gallium and thallium and introduce a range of solid state characterisation techniques. Chapter 7 describes the development of a dip-coating sol-gel method for the growth of thin films of TiO₂ and shows 3D reciprocal space maps of the resulting films. Chapter 8 concerns hard x-ray photoelectron spectroscopy of undoped and Sn-doped TiO₂. Chapter 9 interconnects previous chapters by presenting 2D reciprocal space maps of nano structured epitaxial samples of In₂O₃ grown by the newly developed sol-gel based method. Chapter 10 concludes this thesis with a summary of the results.

Carbon-based materials are poised to be an important class of 21st century materials, for bio-medical, bio-electronic, and bio-sensing applications. Diamond and polymers are two examples of carbon-based materials of high interest to the bio-materials community. Diamond, in its conductive form, can be used as an electrochemical bio-sensor, whilst its nanoparticle form is considered a non-inflammatory platform to deliver drugs or to grow neuronal cells. Polymers, especially when chemically modified, have been used extensively in biological environments, from anti-microbial use to drug delivery. The large-scale use of either material for biological use is limited by two factors: ease of chemical modification and the paucity of knowledge of their surface chemistry in aqueous media. This thesis addresses aspects of both these issues. The first study reported is an in situ study of the adsorption dynamics of an exemplar globular protein (bovine serum albumin, BSA) on nanodiamond using the relatively novel quartz crystal microbalance with dissipation (QCM-D) technique. For the first time, QCM-D enabled the detailed study of protein dynamics (i.e. kinetics, viscoelastic properties, overlayer structure, etc.) onto nanodiamond thin films having various surface chemistry and roughness. The dynamics of protein adsorption is found to be sensitive to surface chemistry at all stages of adsorption, but it is only sensitive to surface roughness during initial adsorption phases. Our understanding of the nanodiamond-biology interface is enhanced by this study, and it suggests that QCM-D is useful for the study of the surface chemistry of nanoparticle forms of inorganic materials. A second study concerns a novel surface functionalization scheme, based on carbene and azo-coupling chemistry, which has been recently introduced as a practical, facile method for modifying the surfaces of polymers. Using modern surface characterization techniques, it is demonstrated that a chemical linker can be attached to polystyrene surfaces using carbene-based chemistry, and that further chemical functionality can be added to this chemical linker via an azo-coupling reaction. In situ studies of protein dynamics at these interfaces were conducted using QCM-D, thus enabling a link between specific protein behaviour and the polymer surface chemical termination chemistry to be made. A third area of study of investigates the use of diamond electrodes as a bio-sensor for dopamine under physiological conditions. For these conditions, ascorbic acid interferes with the dopamine oxidation signal, in ways that render the two signals irresolvable. Various modifications are used in attempts to reduce this interference, including: small and large cathodic treatments, grafting of electro-active polymers, addition of carbon nanotubes, and hydrogen plasma treatment. Those modifications leading to the hydrogen-termination of diamond are shown to work the best. Notably, hydrogen plasma treatment effects the complete electrochemical separation of dopamine and ascorbic acid at a diamond electrode. This is the first time this has been accomplished without adding non-diamond materials to the diamond electrode surface.