Spectroscopic studies of ultrathin bimetallic and oxide films /
Bimetallics including Cu/Pd(111), Pb/Ru(0001) and Pb/Pd(111) have been studied with X-ray photoelectron spectroscopy (XPS). Both XPS and thermal desorption spectroscopy (TDS) show that at room temperature, after completion of the first monolayer of Pb on Ru(0001), further Pb deposition leads to the...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2000.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=728331801&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Bimetallics including Cu/Pd(111), Pb/Ru(0001) and Pb/Pd(111) have been studied with X-ray photoelectron spectroscopy (XPS). Both XPS and thermal desorption spectroscopy (TDS) show that at room temperature, after completion of the first monolayer of Pb on Ru(0001), further Pb deposition leads to the formation of three-dimensional (3D) islands. The Pb 4f₇/₂ binding energy (BE) for the first monolayer of Pb displays a very small shift with respect to that of bulk Pb. In contrast, Pb alloys with the Pd(111) surface at room temperature, as evidenced by the changes of both Pd 3d₅/₂ ]BE and Pd(M₄,₅VV) features. At room temperature, Cu grows on Pd(111) via a layer-by-layer mode. Upon annealing to temperatures higher than 400 K, submonolayer Cu alloys with the Pd substrate. The Cu 2p₃/₂ BE shifts demonstrate that the electronic properties of the Cu monolayer and alloys are significantly perturbed. The core-level shifts are discussed in terms of possible initial and final state contributions. High-resolution electron energy loss spectroscopy (HREELS) and TDS results show that both 3D oxide films and two-dimensional (2D) oxide films formed on Mo(110) produce methoxy intermediates via methanol decomposition. However, on the 2D oxide surface, methoxy decomposition leaves behind an oxygen which is found to form Mo=O, as in the 3D oxide. The availability of such a specific site (on top) is seen to open up the methyl radical reaction pathways. By employing metastable impact electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS), and work function measurements, structural phase transitions of benzene have been identified on the MgO(100)/Mo(100) surface at 100 K. The MgO(100)/Mo(100) electronic structure shown in MIES is dominated by O(2p) features. For both water and methanol, MIES and TDS show molecular adsorption is favored over dissociation on MgO(100)/Mo(100). For water adsorption, a 3D growth mode after the first non-closely packed layer was demonstrated. On the other hand, methanol forms a closely packed, 2D structure for the first layer. Sodium dosed onto a D₂O-precovered MgO surface most likely leads to NaOD formation. It is found that methanol wets the water precovered MgO surface; however, adsorption of water on the methanol precovered MgO surface induces intermixing. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xiv, 180 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 160-175). |