Studies

SUMMARY: Surfaces and interfaces have unfathomable significance for all life-supporting processes, whether simple water condensation or a complex biomolecule interaction. However, only a few techniques are capable of directly observing behavior of water and organic molecules at the interfaces with a submonolayer sensitivity. SEIRAS or surface enhanced infrared absorption spectroscopy is one of them. SEIRAS emerged in the last couple of decades but has only found its application in studies of biological membranes and proteins during the last decade. With this work it was sought to investigate the structural changes in self-assembled monolayers, artificial bilayer lipid membranes, and membrane interaction with the pore-forming toxin melittin in situ using the SEIRAS technique. It was demonstrated, that SEIRAS can be used to study hydrogen bond interactions in several different systems. A valuable insight into the formation and behavior of model lipid membrane systems formed on the gold surface was provided with this work. Finally, SEIRAS setup allowed in situ investigation of pore-forming toxin peptide melittin, confirming its structural changes from unordered to alfa in the first seconds of its interaction with a model membrane.

SUMMARY: Valve metal anodizing is a widely applied and convenient process for obtaining ordered oxide nanomaterials with controllable properties. The anodizing conditions, such as anodizing voltage, type of electrolyte, concentration, and temperature, significantly influence the morphology and composition of the obtained coatings and films. Modifying anodic oxides with the products of electrochemical oxidation of electrolyte components can create additional opportunities for regulating the properties of materials. Therefore, searching for new electrolytes is a prospective area of investigation. In this study, we used the ammonium heptamolybdate and sodium metavanadate additives as corrosion inhibitors to prevent aluminum dissolution at the initial stages of aluminum anodizing in formic acid solutions, thus increasing film growth rate and thickness. The content of carbonaceous species was higher than in oxalic and tartaric anodic alumina films, and the anodizing voltage was lower than in tartaric acid solutions. FTIR, XPS, and Raman spectroscopy established that carbonaceous species were embedded in the anodic alumina as CO2 and CO molecules, carboxylate ions, and carbon species in the sp2 and sp3 states. For the first time, carbonaceous inclusions were extracted from the oxide matrix, and they were shown to exist as luminescent and biocompatible nanoparticles possessing an excitation-dependent emission behavior at 280–450 nm.

SUMMARY: 
This work investigates the usage of nonlinear optical effects in optical fibers to overcome some of the physical limitations that short pulse fiber based generators face. The optical wavelength was converted from 1 µm to visible (648 nm) and near-IR ranges (910-940 nm) by using different photonic crystal fibers. This allows to expand the available wavelength range to those, that do not have a developed amplifying medium. It was also demonstrated experimentally that the setup for this type of frequency conversion can be assembled using all-fiber components. The second chapter of the thesis was dedicated to regenerative pulse shaping by using the Mamyshev regenerative chain. The use of the Mamyshev regenerator allows the shaping of the pulses from different sources through a set number of spectral broadening and filtering cycles. It was determined experimentally and numerically that to shape the pulse, 3-5 roundtrips inside the regenerative chain are required. The shaped pulse becomes nearly independant from the parameters of the initial pulse, such as pulse duration, energy, or spectral width. Mamyshev regenerative chain allows to shape the pulses from different sources, such as a short pulse oscillator or a pulsed laser diode, which generate the pulses with durations in the range of a few tens of picoseconds. The shaped pulses have parameters strictly determined by the parameters of the regenerative chain, and parameters such as pulse energy or spectral width can even be a few times higher compared to the initial pulse parameters.