Tunable nanoporous silicon oxide templates by swift heavy ion tracks technology

Nanoporous silicon oxide templates formed by swift heavy ion tracks technology have been investigated. The influence of the heavy ion characteristics, such as type of ion, energy, stopping power and irradiation fluence on the pore properties of the silicon oxide templates, has been studied. Furthermore, the process of pore formation by chemical etching with hydrofluoric acid has been thoroughly investigated by assessing the effect of etchant concentration and etching time. The outcome of this investigation enables us to have precise control over the resulting geometry of nanopores arrays. As a result, guidelines for the creation of a-SiO2/Si templates with tunable parameters and general recommendations for their further application are presented.

Interaction of ester functional groups with aluminum oxide surfaces studied using infrared reflection absorption spectroscopy

The bonding of two types of ester group-containing molecules with a set of different oxide layers on aluminum has been investigated using infrared reflection absorption spectroscopy. The different oxide layers were made by giving typical surface treatments to the aluminum substrate. The purpose of the investigation was to find out what type of ester-oxide bond is formed and whether this is influenced by changes in the composition and chemistry of the oxide. The extent by which these bonded ester molecules resisted disbondment in water or substitution by molecules capable of chemisorption was also investigated. The ester groups were found to show hydrogen bonding with hydroxyls on the oxide surfaces through their carbonyl oxygens. For all oxides, the ester groups showed the same nu(C = O) carbonyl stretching vibration after adsorption, indicating very similar bonding occurs. However, the oxides showed differences in the amount of molecules bonded to the oxide surface, and a clear relation was observed with the hydroxyl concentration present on the oxide surface, which was determined from XPS measurements. The two compounds showed differences in the free to bonded nu(C = O) infrared peak shift, indicating differences in bonding strength with the oxide surface between the two types of molecules. The bonding of the ester groups with the oxide surfaces was found to be not stable in the presence of water and also not in the presence of a compound capable of chemisorption with the aluminum oxide surface.

Interaction of anhydride and carboxylic acid compounds with aluminum oxide surfaces studied using infrared reflection absorption spectroscopy

The chemical bonding of three different anhydride and carboxylic acid based compounds with a set of differently prepared aluminum substrates has been investigated using infrared reflection absorption spectroscopy. The compounds were selected to model typically used adhesives, coatings, and self-assembling monolayers. The purpose of the investigation was to study the interaction of these functional groups with the aluminum oxide surface and to determine whether this interaction is influenced by the changes in chemistry and composition of the oxide layer. The extent to which the compounds resisted disbondment in water was also investigated. The oxide layers on the differently prepared substrates were all found to be capable of hydrolysis of the anhydride group, resulting in the formation of two carboxylic acid groups. Subsequently, both of the carboxylic acid groups became deprotonated, to form a coordinatively bonded carboxylate species. The same behavior was also observed for monofunctional carboxylic acids. For all different oxides layers, the carboxylate was found to be coordinated in a bridging bidentate way to two aluminum cations in the oxide layer. The oxide layers showed however clear differences in the amount of molecules being chemisorbed. A relation was established with the amount of hydroxyls present on their surfaces, as determined from X-ray photoelectron spectroscopy measurements. The coordinative bonding of a monofunctional carboxylic acid group to the oxide surface was found to be not stable in the presence of water, while a bifunctional carboxylic acid group could resist displacement by water for a prolonged period of time.