| By collecting IRAS spectra over a broad range of gold particle sizes, CO pressures, and sample temperatures, a wealth of thermodynamic information on CO adsorption on gold catalysts has been produced. Energetically, CO on 0.5 MLE Au/TiO2 behaves nearly identically to CO on bulk gold single crystals, although the vibrational energies are slightly different. As the Au particle size decreases, the heat of CO adsorption increases while vibrational frequencies remain essentially unchanged, pointing toward a particle size effect upon the CO adsorption energy. When trace oxygen is introduced into the system, the CO vibrational frequency blue shifts at higher coverage while the heat of adsorption for all measured coverages drops significantly, particularly at the zero coverage limit. This result confirms the presence of oxygen on the Au particles either as a reactant or as a barrier to CO adsorption. The low concentration of oxygen introduced to produce such an effect suggests an exceptionally strong interaction between oxygen and supported gold systems.; IRAS, TPD, STM, and AES were used to characterize Ru3(CO) 12 decomposition on a titania thin film and TiO2(110) single crystal. It was found that the carbonyl precursor decomposes cleanly, forming small clusters of ruthenium and rows of ruthenium atoms collinear with the [001] surface vector of the single crystal substrate. It was shown by direct comparison of infrared studies to published work and indirect comparison of published EXAFS to the current STM data that vapor deposition of the precursor forms substantially different surfaces than wet impregnation.; An improved IRAS system was designed and built taking advantage of a stable, rigidly mounted infrared spectrometer and the technique of polarization modulation (PM-IRAS). This system's effectiveness at measuring in situ CO adsorption morphologies was demonstrated at pressures ranging over nine orders of magnitude, up to 600 Torr. |
