This thesis systematically studies the physicochemical properties of non-planar, propeller-shaped, polycyclic aromatic hydrocarbons. The synthesis of several so-called propellerenes is described on... Show moreThis thesis systematically studies the physicochemical properties of non-planar, propeller-shaped, polycyclic aromatic hydrocarbons. The synthesis of several so-called propellerenes is described on a gram scale, using optimized procedures aimed at using less hazardous reagents and reducing the amount of organic solvent used. The conformational behavior of several propellerenes is studied experimentally using variable temperature NMR, and findings corroborated using high-level DFT computations. The origin of the conformational preference of propellerenes is elucidated using a novel adaptation of the activation-strain model. By computationally dissecting propellerenes into its constituent parts, the preference of these parts can be analyzed. The spectroscopic properties of conformationally pure propellerenes are studied experimentally, and experimental findings explained on a molecular orbital level, using time dependent DFT computations. Lastly, the supramolecular behavior of propellerenes is studied by the production of molecularly thin films, using the Langmuir-Blodgett technique. These thin films are imaged using electron microscopy, the molecular dynamics at the air-water interface studied computationally, and the physical properties of the thin films quantified using AFM nanoindentation. These propellerene-based thin films are, for the first time, found able to be free-standing over nanometer distances. Combined, this thesis establishes propeller-shaped, polycyclic aromatic hydrocarbons as an independent field of study. Show less
In this thesis I present my research on the physics of some important processes in the production of thin films. I studied physical vapour deposition (PVD) and thin film modification through ion... Show moreIn this thesis I present my research on the physics of some important processes in the production of thin films. I studied physical vapour deposition (PVD) and thin film modification through ion bombardment using a newly developed, high-speed scanning tunneling microscope (STM). The instrument has the special property that it can be tilted and azimuthally rotated to allow atom or ion beams a direct line-of-sight access to the region of the surface that is being imaged by the STM tip. With the microscope I have recorded STM movies (available as supplementary material) that offer a unique insight into the atomic surface processes that occur during thin film growth and ion beam sputtering. The __real-time STM__ was applied to the study of some key steps in the fabrication of Mo-Si multilayer optical coatings. I have investigated the non-idealities of these optics, i.e. the alloying of Mo and Si during deposition and the surface roughness formation of a deposited layer. Furthermore, I successfully used the STM to find a possibility to smooth a rough Mo layer after its deposition by means of ion bombardment. Show less
We study the shear flow of two-dimensional foams, i.e., a monolayer of bubbles floating on a soapy solution. We successfully connect local and global flow behaviour
The research in this thesis comprises two separate topics: single-molecule spectroscopy and resonant Raman spectroscopy. The first part concerns single-molecule (SM) spectroscopy on polyethylene ... Show moreThe research in this thesis comprises two separate topics: single-molecule spectroscopy and resonant Raman spectroscopy. The first part concerns single-molecule (SM) spectroscopy on polyethylene (PE) films. Ultra thin (200 nm) films of pure high density PE were produced by spincoating. By determining the position (accuracy 10 nm) and in-plane orientation (acc. 5 deg.) of single 2.3,8.9-dibenzanthanthrene (DBATT) guest molecules, by means of SM microscopy and spectroscopy respectively, we demonstrated that these thin PE films have a shish-kebab morphology, instead of the spherulitic morphology common in thicker PE films. We have also investigated the alignment process of individual quest chromophores by stretching thicker (50 um), low density PE films. Using SM spectroscopy, we have shown that individual guest chromophores are not better aligned along the stretch direction, as draw ratio increases. Instead alignment occurs suddenly, due to the destruction and (oriented) reformation of local crystalline regions and subsequent adsorption of chromophores. Each chromophore's orientation is determined by specific interactions with the oriented PE crystal surface. The second part of this thesis concerns a quantum-chemical analysis of the resonant Raman spectrum of the carotenoid spheroidene reconstituted in the photosynthetic reaction center (RC) of Rhodobacter sphaeroides. Our analysis demonstrates that spheroidene can adopt at least two cis forms in the RC. One of these has been conclusively shown to be the 15,15'-cis structure. Show less
A remarkable feature of block copolymer systems is their ability to self-assemble into a variety of ordered structures with domain sizes in the mesoscale range. One of the open questions is the... Show moreA remarkable feature of block copolymer systems is their ability to self-assemble into a variety of ordered structures with domain sizes in the mesoscale range. One of the open questions is the dynamics of structure formation, which can be highly dependent on external fields often present in industrial conditions, such as shear, temperature gradients and confinement, or external fields which are employed to manipulate the structure, such as electric and magnetic fields. An understanding of the external field effects and effects of architecture and composition of block copolymer systems is crucial, since these factors may have a large impact on the structure formation and consequently on the structural and physical properties of the final product. In the present thesis I have focused on the comparison of results of the existing Dynamic Self Consistent Field Theory (DSCFT) with experimental observations for specific experimental systems as well as on the prediction of generic dynamic phenomena for chosen model systems. A detailed comparison with experiments was possible due to the development of such state-of-the-art experimental techniques as dynamic Scanning Force Microscopy. We have shown that the static behavior as well as the dynamics of phase transitions under an external field is well described by the theory for a number of experimental systems. This thesis demonstrates that this symbiotic approach is valuable; the experiments validate the theoretical calculations and the calculations rationalize the experimental observations. Eventually, the method can be employed to make predictions and propose improvements for yet less understood experimental and industrial systems. Show less
