| dc.contributor.author | Yang, Rui | |
| dc.date.accessioned | 2019-01-15T18:39:26Z | |
| dc.date.available | 2019-01-15T18:39:26Z | |
| dc.date.issued | 2019-01-15T18:39:26Z | |
| dc.identifier.uri | http://hdl.handle.net/10222/75072 | |
| dc.description | First, experimental XAS at Au L3-edge was employed to investigate the bonding properties of Au44(SR)28. A multi-shell XAS fitting procedure was developed to probe its local structure from the gold perspective. In addition, temperature-dependent XAS was used to study the dynamic bonding behavior of the NCs. By comparing with the XAS fitting results of two other NCs, Au28(SR)20 and Au36(SR)24, a unique size-dependent trend was discovered for this series of FCC-like AuSR NCs. The size-dependent bonding behavior of these NCs was accounted for by closely examining the core structure of the three NCs. Second, Au L3-edge XAS was used to study the bonding properties of HCP-like Au30(SR)18. By comparing with icosahedral-like Au25(SR)18 and FCC-like Au36(SR)24, X-ray absorption near edge structure (XANES) analysis in association with site-specific simulations was performed to study the bonding properties of surface gold sites. Temperature-dependent XAS measurements were employed to help to examine the thermal bonding behavior in the first Au-Au shells. Finally, the bonding properties of BCC-like Au38S2(SR)20 was presented by comparing its XAS results with the bi-icosahedral like Au38(SR)24 due to their similar composition. XANES, together with site-specific simulations, was employed to study their bonding properties from the surface site perspective. The special surface Au-Au bonding properties of the BCC-like NCs were found to be connected with its unusual sulfide gold unit. The ligand effect on solvation-induced structure change was further investigated on these NCs by multi-shell EXAFS fitting, suggesting the ligand structure can be used to control the solution-phase bonding behavior of the NCs. Overall, this work highlights the important role of the core geometry in controlling the NC core, surface and ligand bonding behavior. The XAS methodology demonstrated in this thesis employing the first derivative XANES and simulations, in association with the multi-shell EXAFS analysis, can also be extended to the studies of other metal NC systems. | en_US |
| dc.description.abstract | Research on thiolate-protected gold nanoclusters (AuSR NCs) has recently attracted a great deal of interests due to their intriguing atomic structure and promising applications in catalysis, nanoelectronics, bio-detection, and so on. Among the AuSR NCs reported so far, the NCs with face centered cubic (FCC)-like core structure are particularly interesting because of its similar geometry to bulk gold. In addition, hexagonal-close-packed (HCP)-like and body-centered cubic (BCC)-like AuSR NCs have also been discovered recently, and thus it will be important to understand how such new core geometry will influence their bonding properties.
In this thesis, the focus is placed on the experimental and theoretical X-ray absorption spectroscopy (XAS) studies of the local structure and bonding properties of FCC-like, HCP-like and BCC-like AuSR NCs: Au44(SR)28, Au30(SR)18 and Au38S2(SR)20. | en_US |
| dc.language.iso | en | en_US |
| dc.subject | Thiolate protected Au NCs | en_US |
| dc.subject | X-ray absorption spectroscopy | en_US |
| dc.subject | Face-centered cubic (FCC)-like | en_US |
| dc.subject | Hexagonal-close-packed (HCP)-like | en_US |
| dc.subject | Body-centered cubic (BCC)-like | en_US |
| dc.subject | Negative thermal expansion | en_US |
| dc.subject | Electronic and bonding properties | en_US |
| dc.title | X-ray Absorption Spectroscopy Studies of Thiolate-protected Gold Nanoclusters with FCC-, HCP- and BCC-like Core Geometry | en_US |
| dc.date.defence | 2017-11-24 | |
| dc.contributor.department | Department of Chemistry | en_US |
| dc.contributor.degree | Master of Science | en_US |
| dc.contributor.external-examiner | n/a | en_US |
| dc.contributor.graduate-coordinator | Mark Stradiotto | en_US |
| dc.contributor.thesis-reader | Heather Andreas | en_US |
| dc.contributor.thesis-reader | Amares Chatt | en_US |
| dc.contributor.thesis-supervisor | Peng Zhang | en_US |
| dc.contributor.ethics-approval | Not Applicable | en_US |
| dc.contributor.manuscripts | Yes | en_US |
| dc.contributor.copyright-release | Not Applicable | en_US |
