Die vorliegende Arbeit beschäftigt sich mit der Herstellung und Charakterisierung von dünnen Schichten im ternären System B-C-N. In diesem System sind einerseits die härtesten heute bekannten Materialien (Diamant, c-BN) enthalten, aber andererseits auch Stoffe mit unterschiedlichsten elektrischen Eigenschaften (Graphit, h-BN). Es besteht daher das Bestreben, verschiedene bekannte Materialien zu kombinieren und so deren Eigenschaften in gewünschter Weise einzustellen. Allerdings wird sowohl experimentell als auch theoretisch des öfteren eine Separation in BN- und C/CNx-Phasen beobachtet. Im Rahmen dieser Arbeit wurden Schichten über einen weiten Stöchiometriebereich mittels reaktiver DC-Magnetronzerstäubung hergestellt und untersucht. Schwerpunkt wurde dabei auf die Analyse der Struktur und des Bindungszustandes sowie die mechanischen Eigenschaften Härte und Elastizitätsmodul gelegt. Es wird diskutiert, in welchen Elementezusammensetzungen wirkliche ternäre Verbindungen entstanden sind und ein Zusammenhang zwischen Struktur und mechanischen Eigenschaften in Form einer empirischen Formel abgeleitet.

Using photoemission spectroscopy (PES) the interface between the amino acid L-cysteine and a Au substrate was characterized to determine its electronic and chemical structure. L-cysteine was deposited on a Au substrate in several experiments via dipping into solution or via evaporation. The depositions were performed in several steps. Between deposition steps x-ray photoemission spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS) measurements were taken. XPS was used to characterize the chemical interaction at the interface while UPS was used to determine the orbital line-up at the interface and the highest molecular orbital (HOMO) structure of L-cysteine. The results indicate the formation of an interface state at approximately 1.5 eV above the L-cysteine HOMO.

P3HT (Poly(3-hexylthiophene)) is an organic polymer that shows promise as an active material in semiconducting electronics. It is important to study the electronic properties of this material in order to determine its efficacy in such devices. However, many current studies of thiophene only examine the oligomer, since it is a simpler material to investigate. In this study, several P3HT interfaces were analyzed to determine their electronic properties. The P3HT was deposited on Au, highly-ordered pyrolitic graphite (HOPG), and indium tin oxide (ITO) substrates via electrospray deposition. The depositions were performed in several steps, with x-ray photoemission spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS) measurements taken between each step without breaking the vacuum. The resulting series of spectra allowed orbital line-up diagrams to be generated for each interface, giving detailed analysis of the interfacial properties, including the charge injection barriers and interface dipoles. The results, when compared to similar oligomer-based investigations, show a difference in the orbital line-up between oligomeric and polymeric P3HT junctions.

Methods for integrating enzyme systems with electrochemical reactions having applications to diagnostic sensing are described. Diagnostic tests that include biological molecules can be classified as biosensors. Existing testing methods often require trained technicians to perform, and laboratory settings with complex infrastructure. The theme of this dissertation is the development of methods that are faster, easier to use, and more applicable for non-laboratory environments. These goals are accomplished in systems using enzymatic catalysis and galvanic processes. Two biosensors with specific model pathologies have been designed and demonstrated in this study. The first assay senses a DNA fragment representing the Epstein Barr virus and uses enzyme-mediated Ag deposition over a v microfabricated chip. The chip contains a specially designed pair of electrodes in an interdigitated array (IDA). Detection is signaled by a change in the resistance between the two electrodes. The second biosensor discussed in this study is targeted towards the digestive enzyme trypsin. It is selfpowered due to its construction within an open-circuit galvanic cell. In this system, a small volume of blood serum is introduced onto the device over barriers made of protein and Al that block the anode from solution. In the presence of trypsin, the protein gel is rendered more permeable to sodium hydroxide. Adding hydroxide initiates the dissolution of the Al layer, closing the cell circuit and illuminating a light-emitting diode (LED). A relationship was observed between LED illumination time and trypsin concentration. Biosensors that utilize enzymes to generate or amplify a detectable signal are widely used, and the final project of this study uses a nanoparticle based approach to protect the catalytic activity of alkaline phosphatase (AlkP) from hostile chemicals. By incubating Au colloid with AlkP overnight and adding Ag+, core@shell nanoparticles of Au@Ag2O can be isolated that show AlkP activity. The resulting enzyme-metal composite material was analytically characterized and demonstrated greater activity in the presence of organic inhibitors relative to either wild type vi or Au colloid-associated AlkP without the Ag2O shell. The stabilization procedure is complete in one day using a onepot synthesis. This method may provide opportunities to carry out biosensing chemistry in previously incompatible chemical environments. / text

Στην παρούσα διπλωματική εργασία αναλύονται λεπτά υμένια (thin films) διαφόρων πολυμερικών ή ολιγομερών οργανικών ενώσεων, με την επεξεργασία μετρήσεων που είχαν ληφθεί με την επιφανειακά ευαίσθητη τεχνική της φασματοσκοπίας φωτοηλεκτρονίων από ακτίνες Χ (XPS). Από την ανάλυση των φασμάτων XPS προκύπτουν συμπεράσματα τόσο για την παρουσία συγκεκριμένων χημικών στοιχείων στα δείγματα (ποιοτική ανάλυση) όσο και για την συγκέντρωση των στοιχείων αυτών στην περιοχή ανάλυσης (ποσοτική ανάλυση). / This thesis analyzed thin films (thin films) various polymeric or oligomeric organic compounds, the processing of measurements taken with the surface sensitive technique of spectroscopy X-ray photoelectron (XPS). From the analysis of XPS spectra resulting conclusions as to the presence of certain chemical elements in samples (qualitative analysis) and for the concentration of these elements in the analysis (quantitative analysis).

The heart is one of the most important organs of the human body and cardiovascular diseases remain the biggest cause of deaths worldwide. Today, due to the aging of the population and the growing demand for cardiovascular implants, improving the performance of artificial surfaces of vascular prostheses is highly desired. The common material for fabricating prostheses, such as stents used to remedy narrow and weak arteries, is Fluorocarbon polymers or expanded Polytetrafluoroethylene (ePTFE, Gore-tex). Although these polymers are well known for chemical inertness, thermal stability and low friction, they can cause early thrombosis (forming clot) and coagulation in blood vessels and require periodic replacement. Modifying the surface properties of Polytetrafluoroethylene (PTFE) by coating with carbon-based materials may improve its blood compatibility. Carbon-based coatings have properties similar to biomedical components, such as low friction, bioinertness, high wear resistance and exceptional hardness. Plasma processing methods are commonly used for coating thin films on various materials including carbon-based components. Plasma-based processes are also widely used in the aerospace, automotive, steel and biomedical industries. For example, extending the lifetime of surgically implanted hip joints and cutting tools are biomedical and industrial applications of plasma-based material processing respectively. Plasma-assisted deposition techniques are commonly used for carbon-based coating including nitrogen-doped amorphous carbon (a-C) films. In this thesis, PTFE samples with different thickness and roughness characteristics are used as substrates and diamond-like carbon (DLC) is deposited on them by simultaneous plasma-assisted sputtering and chemical vapour deposition (CVD). Hot filament plasma and ICP (Inductively coupling plasma) are used to coat DLC on PTFE and silicon (Si) substrates under various plasma conditions. The latter is the first report on the techniques to coat DLC by ICP plasma sputtering. This new technique (ICP-sputtering) is developed to improve low deposition rate and high temperature deposition of previous method (Hot filament plasma sputtering). Advantageous of this new developed method (ICP-sputtering) are discussed and compared with the previous method in this thesis. Various amount of nitrogen is introduced to the plasma chambers and the effect of nitrogen dopant is also studied using different characterization techniques for chemical, electronic and morphological properties of coated films. sp2 and sp3 contents were also estimated in amorphous carbon (a-C) and nitrogenated amorphous carbon (a-CN) films. Characterization techniques used for in this thesis are including SEM (scanning electron microscopy), AFM (atomic force microscopy), Raman spectroscopy, XAS (x-ray absorption spectroscopy), XES (x-ray emission spectroscopy), XPS (x-ray photoelectron spectroscopy) and XRD (x-ray diffraction).

Darbo tikslas yra ištirti atkaitintų prie aukštų temperatūrų vakuume La2O3 sluoksnių Rentgeno fotoelektronų spektrus. Darbe aprašyti Rentgeno fotoelektronų spektroskopijos (RFS) (XPS - X-ray photoelectron spectroscopy) metodo, naudojamo įvairių medžiagų paviršių cheminei sudėčiai nustatyti, pagrindai. Pirmame skyriuje aprašyti: La2O3 oksidiniai junginiai ir jų tyrimų metodika, plonų nanostruktūrizuotų medžiagų sluoksnių nusodinimo iš dujų fazės (plazmos) metodas- magnetroninis dulkinimas (magnetron sputtering), aparatūra ir zolis – gelis metodas. Antrajame skyriuje aprašytas Rentgeno fotoelektroninės spektroskopijos metodas, pagrindinė RFS aparatūra bei teorinė dalis. Trečiasis skyrius yra skirtas Rentgeno fotoelektroninių spektrų matavimų, naudojant spektrometrą XSAM 800 (Kratos Analytical, Didžioji Britanija) ypatumams ir bandinių gamybos metodikai aptarti. Pateiktas išsamus La2O3 sintezės zolių-gelių metodu technologijos aprašymas. Ketvirtajame skyriuje pateikiami eksperimentiniai rezultatai gauti, matuojant La2O3 Rentgeno fotoelektronų spektrus. Darbo pabaigoje yra pateikiamos išvados, kurios galėtų būti naudingos, tobulinant La2O3 bandinių gamybos technologiją. Gautas rezultatas: nustatyta, kad zolių – gelių technologija leidžia paprastais metodais, nenaudojant sudėtingos aparatūros, susintetinti La2O3. / The aim of presented work was to synthesis by using sol-gel technology and investigate the X-ray photoelectron spectra (XPS) of La2O3 thin films in the annealed high temperature vacuum. In the present work we described the essentials of the method of X-ray photoelectron spectroscopy, used to determine chemical composition of various materials. In the first part are described: La2O3 oxide compounds and the methods of the their production from the gas phase – magnetron sputtering and sol – gel method. The second part describes the X- ray photo-electronic spectroscopy method, basic XPS equipment and theoretical part. In the third part we discussed the peculiarities and methodology of spectrometer XSAM 800 (Kratos Analytical, Great Britain) samples production while measuring X-ray photoelectron spectra. The thorough description of the technology by synthesis of La2O3 sol-gel method was provided. The fourth part presents the experimental results obtained by measuring the La2O3 X-ray photoelectron spectra. In the end of the work conclusions are produced that could be useful in improving production technology of La2O3 samples. Obtained results: we identified that sol-gel technology allows to synthesize La2O3 by simple methods, without using sophisticated equipment.

The thin films of oxide xerogels and bronzes and molecular oxide xerogels and bronzes of vanadium compounds were synthesized by sol-gel technology method. The chemical composition of mentioned compounds was investigated using XPS method in order to determine the valence of metal ions. It is shown that it is possible to produce the thin films of vanadium oxide bronzes using simple methods. The possibility to use vanadium-ammonium oxide hydrated compounds as materials for producing the ammonium sensors is shown in the dissertation. / Šiame darbe panaudojant zolis-gelis technologiją, susintetinti vanadžio junginių oksidinių kserogelių ir bronzos bei molekulinių oksidinių kserogelių ir bronzų plonieji sluoksniai. Visų minėtų medžiagų cheminė sudėtis ištirta Rentgeno fotoelektronų spektroskopijos metodu, siekiant nustatyti metalų jonų valentines būsenas. Panaudojant zolis-gelis technologiją, galima gana paprastais metodais, nenaudojant sudėtingos technologinės įrangos, gaminti vanadžio oksidinių bronzų plonuosius sluoksnius. Vanadžio amonio hidratuoti oksidiniai junginiai gali būti naudojami kaip medžiagos amoniako dujų jutikliams gaminti.

Protein PEGylation (covalent attachment of poly(ethylene glycol) or PEG to proteins) is an excellent example of a drug delivery system that improves pharmacokinetics and pharmacodynamic properties of therapeutics. However, although PEGylation is clinically proven and attracts both scientific and commercial interest, the technique is associated with many process constraints, in particular related to controlling the number of conjugated PEG chains. A novel, solid-phase PEGylation methodology was attempted to overcome the drawbacks of the commonly used solution-phase methods for preparing PEGylated products. The solid-phase PEGylation methodology involved conjugating protein onto a tethered PEG derivative attached onto a solid matrix, followed by hydrolytic cleavage of the PEG chain from the solid matrix under mild conditions to yield PEGylated protein in free solution. PEGs with molecular weights (MWs) 2000 and 4000 Da were used and a heterobifunctional PEG derivative, α-(β-alanine)-ω-carboxy PEG, with a cleavable β-alanine ester terminal was prepared for surface grafting and protein conjugation. The amine terminal of this PEG derivative was used for grafting PEG onto carboxy functionalized hydrophilic Sephadex and hydrophobic polystyrene derivatives. The free carboxyl terminal was used for protein conjugation via amine coupling. A kinetic study of PEG-surface grafting was performed to understand the influence of a number of parameters on the PEG surface concentration and its conformation, including temperature, reaction time, nature of the matrix, solvent and base, and MW of PEG. PEG grafted matrices were characterized using various surface characterization tools including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Higher PEG grafting was observed with polystyrene matrices (up to 0.3 mmol/g) than either of the Sephadex derivatives (less than 0.15 mmol/g) using both molecular weights. Detailed surface characterization using XPS studies showed a layer thickness of 11.87 nm was achieved with polystyrene matrices using 4000 Da PEG derivatives after a grafting period of 72 hours at 40°C, indicating the presence of brush conformations for the grafted PEGs. In contrast, mushroom conformations were observed for PEG molecules grafted on both carboxymethyl and carboxypentyl Sephadex derivatives after the same reaction period, with a layer thickness of 2.62 nm and 4.14 nm respectively. Optimized PEG grafting and hydrolysis conditions were developed for solid-phase protein PEGylation using Cytochrome c as a model protein. The presence of PEGylated species were detected by size exclusion chromatography (SEC) from Sephadex derivatives but were absent when using polystyrene matrices. Both Sephadex derivatives gave mainly multi-PEGylated species with poor yields, in place of the expected mono-PEGylated products. A solution-phase PEGylation using the same PEG derivatives was performed successfully and various PEGylated species were identified and characterized using SEC and gel electrophoresis, based on their viscosity radius. An examination of the surface characteristics of the PEG-grafted was carried out by XPS, showing that protein conjugation was greatly influenced by surface force interactions, which depended on the PEG grafting densities and the nature of the solid matrices. Finally, fluorescent images obtained using confocal microscope with fluorescein isothiocyanate labelled Cytochrome c provided supporting evidence regarding the factors that constrained the solid-phase PEGylation process.

This thesis concerns new hydrogen- and polarity-related effects in the photoluminescence of ZnO single crystal wafers and the relationship between surface electron accumulation and surface hydroxyl coverage on different ZnO surfaces. A comparative study of the low temperature photoluminescence of various types of hydrothermal and melt-grown ZnO wafers revealed several new hydrogen-related exciton recombination lines and a number of consistent polarity-related differences in the PL emission from different crystallographic surfaces. Temperature-dependent PL measurements were extensively used to distinguish the ground and excited state transitions involved in these effects. ZnO samples of different surface polarity were annealed in oxygen and nitrogen gases and in hydrogen-containing forming gas mixtures in an attempt to identify the origin of these new PL features. The well known aluminium-related I_₆ recombination line was resolved into two separate features in hydrothermal ZnO, and the new component I6-H (3.36081 eV) was found to repeatedly quench and then re-emerge after annealing in oxygen and forming gas, respectively. A model involving an aluminium - lithium - hydrogen defect complex was proposed for I6-H and further tested via hydrogen and deuterium implantation experiments on hydrothermal ZnO wafers with different lithium concentrations. These experiments also provided evidence for the involvement of a different lithium-hydrogen defect complex in other hydrogen-related emission lines I₄b,c (3.36219 eV and 3.36237 eV) unique to hydrothermal ZnO. In addition, a broad Gaussian-shaped feature observed in the near-band-edge PL emission from the O-polar (000‾1), a-plane (11‾20) and r-plane (1‾102) faces of ZnO was shown to be surface sensitive and also related to hydrogen. The involvement of hydrogen in the chemical and electronic properties of different ZnO surfaces was also investigated. The thermal stability of the hydroxyl termination and the associated downward surface band bending on the polar and non-polar surfaces of ZnO was studied by synchrotron and real-time photoelectron spectroscopy, both during and after annealing and subsequent H₂O/H₂ dosing in ultra-high vacuum conditions. On the O-polar face, the band bending could be reversibly switched over a range of approximately 0.8 eV by adjusting the surface H-coverage using simple UHV heat treatments and atmospheric exposure. A transition from electron accumulation to electron depletion on the O-polar face was observed at a H-coverage of approximately 0.9 monolayers. In contrast, the downward band bending on the Zn-polar face was significantly more resilient and electron-depleted surfaces could not be prepared by heat treatment alone. This was also the case for in situ cleaving in UHV conditions which failed to produce hydroxyl-free surfaces due to migration of hydrogen from the bulk to the cleaved surface. Interestingly, the thermal stability of the hydroxyl termination on the a-plane (11‾20) and m-plane (10‾10) surfaces was signiifcantly lower than on the polar faces due to the availability of a lower energy desorption pathway and the electrostatic stability of these non-polar surfaces in their clean, bulk terminated form. The surface band bending on the non-polar ZnO surfaces was also found to be directly related to their OH coverage with a transition from downward to upward band bending, similar to that observed on the O-polar face, as the OH coverage was reduced. Thermal admittance spectroscopy and deep level transient spectroscopy was used to investigate the effect of lithium removal on the defect nature of hydrothermal ZnO. A number of new defects were introduced by the high temperature (1100-1400°C) annealing/re-polishing process used to reduce the lithium concentration, particularly E₁₉₀ (also known as T2) which is thought to be related to Zn vacancies. Significantly, both the E₅₀ defect level and the I6-H PL emission line were absent after lithium (and hydrogen) removal suggesting an association of both these features with the same aluminium - lithium - hydrogen defect complex.