Chemistry of thin films of aluminum oxide and platinum particles on aluminum oxide, and the detection of hydrogen using FTMS

Aluminum oxide is used extensively as a catalyst and catalyst support. As a model for these systems, non-hydroxylated thin films of γ-aluminum oxide are grown on NiAl(001), and the chemistry on the surfaces is probed using laser induced desorption Fourier transform mass spectrometry (LID-FTMS). Hydroxylated surfaces can be produced by exposing a non-hydroxylated surface to water at room temperature.; This dissertation shows that the hydroxyl groups play an important role in the chemistry on the aluminum oxide surface. On the hydroxylated surface, the 1,3-butadiene dimerizes to form 4-vinyl-cyclohexene via a Diels-Alder mechanism. Molecules such as maleic anhydride and pyridine do not react to form additional products on either the hydroxylated or non-hydroxylated surfaces, but the desorption behavior is affected by the presence of hydroxyl groups. When 1,3-butadiene was dosed onto a surface that was pre-exposed to a dienophile, such as maleic anhydride, acrolein or acrilonitrile, there was no evidence for a reaction between the two molecules.; A platinum evaporator was constructed to deposit platinum on thin films of non-hydroxylated aluminum oxide to model supported metal catalysts. The platinum deposition was characterized using carbon monoxide uptake on the platinum particles. The CO uptake results were consistent with a hemispherical particle model.; This dissertation also describes a major upgrade of the FTMS system that would allow us to detect hydrogen simultaneously with heavier ions for the first time using FTMS. It was found that we were unable to use impulse excitation to excite hydrogen to a large enough radius that it could be detected. RF excitation could be used to excite hydrogen, but the RF parameters were different than those used for larger molecules. The ion intensity for hydrogen was significantly lower than what was expected for the number of hydrogen ions in the chamber due to the high kinetic energy H₂+ ions reacting with molecules in the background and z-ejection of ions. Lowering the magnetic field from ∼0.6 T to ∼0.3 T dramatically increased the hydrogen ion intensity, while larger molecules could still be trapped and detected. It is now possible to detect hydrogen simultaneously with larger molecules using FTMS.