Characterizing the Optical and Electrochemical Properties of Monolayer-Protected Noble Metal Nanoclusters

Gold, silver, and other nanoclusters protected by a monolayer of monothiolate or dithiolate ligand can be synthesized into a variety of compositions and core structures depending on the type of ligand used and reaction conditions. Unique size or composition dependent physicochemical properties emerge ranging from being molecular-like to plasmonic toward bulk metal. This dissertation focuses on the characterization of optical and electrochemical and other related properties of newly synthesized and previously established Au and Ag nanoclusters. Chapter one provides an overview of the gold and silver nanoclusters including both fundamentals and applications. In chapter two, phase transfer strategy is adopted to overcome the restraints of using water as an electrochemical solvent. Redox activities in a much wider potential were resolved for newly synthesized aqueous soluble Au nanoclusters stabilized by mercaptosuccinic acid and lipoic acid (LA) and the previously reported Au22LA12. In chapter three, spectroelectrochemistry analysis reveals unprecedented details in electronic transitions from the Au130(p-MBT)50 nanoclusters (sample obtained through the collaboration with Jin’s group). An energy diagram is proposed from the combined optical and electrochemical characterizations in reference to the ultrafast spectroscopy results. Together with the Au130 stabilized by a mixed mono- and di-thiolate ligand monolayer reported earlier by our group, a significant conclusion is reached that up to Au130, a clear energy band gap remains corresponding to molecular energetics. Full transition to metallic will likely occur at larger sizes with appropriate lattice structures. In chapter four, a new silver nanocluster is synthesized with the lipoic acid as its protecting ligands. Optical, electrochemical, and other features were studied to characterize this new cluster. Intense absorbance features along with high but unstable luminescence were observed. Like its gold counterparts, ligand oxidation was observed by FTIR. Further mass spectrometry data is needed to propose a molecular composition

Mottled Duck in Nebraska

The two major US populations of Mottled Duck occur in Florida and along the Gulf Coast in Louisiana and Texas, with local breeding inland to “southeast Colorado, western Kansas, Oklahoma (rarely), and northeast Texas” (AOU Checklist of North American Birds, Sixth Edition, 1983). Palmer (Handbook of North American Birds, Vol. 2, 1976) notes that Mottled Duck bred in 1963 at Cheyenne Bottoms, Kansas, and that some individuals occur inland beyond the usual breeding range during the post-breeding period. Presumably these inland. records pertain to birds from the Texas-Louisiana population, as the Florida birds are generally considered nonmigratory. Thus the occurrence of Mottled Duck in Nebraska is a possibility, especially in the fall

The Red-Naped Sapsucker in Nebraska

The Red-naped Sapsucker (Sphyrapicus nuchalis) was for many years accorded subspecific status within Yellow-bellied Sapsucker (Sphyapicus varius), but the American Ornithologists’ Union recently revised this opinion, and now regards nuchalis as a “good” species (Auk 102:680). Red-naped Sapsucker can be added to the Nebraska (species) list on the basis of three specimens in the collection of the University of Nebraska State Museum (UNSM). The breeding range of Red-naped Sapsucker includes the Rocky Mountains east of the Cascades from southwest Canada south to central Arizona and it winters in much of northern Mexico, north as far as the southern part of its breeding range (The NOU Checklist of North American Birds, Sixth Edition, 1983)

The Red-Naped Sapsucker in Nebraska

The Red-naped Sapsucker (Sphyrapicus nuchalis) was for many years accorded subspecific status within Yellow-bellied Sapsucker (Sphyapicus varius), but the American Ornithologists’ Union recently revised this opinion, and now regards nuchalis as a “good” species (Auk 102:680). Red-naped Sapsucker can be added to the Nebraska (species) list on the basis of three specimens in the collection of the University of Nebraska State Museum (UNSM). The breeding range of Red-naped Sapsucker includes the Rocky Mountains east of the Cascades from southwest Canada south to central Arizona and it winters in much of northern Mexico, north as far as the southern part of its breeding range (The NOU Checklist of North American Birds, Sixth Edition, 1983)

The medical student

The Medical Student was published from 1888-1921 by the students of Boston University School of Medicine

Mottled Duck in Nebraska

The two major US populations of Mottled Duck occur in Florida and along the Gulf Coast in Louisiana and Texas, with local breeding inland to “southeast Colorado, western Kansas, Oklahoma (rarely), and northeast Texas” (AOU Checklist of North American Birds, Sixth Edition, 1983). Palmer (Handbook of North American Birds, Vol. 2, 1976) notes that Mottled Duck bred in 1963 at Cheyenne Bottoms, Kansas, and that some individuals occur inland beyond the usual breeding range during the post-breeding period. Presumably these inland. records pertain to birds from the Texas-Louisiana population, as the Florida birds are generally considered nonmigratory. Thus the occurrence of Mottled Duck in Nebraska is a possibility, especially in the fall

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Cover title.Mode of access: Internet

Transitions in Discrete Absorption Bands of Au₁₃₀ Clusters upon Stepwise Charging by Spectroelectrochemistry

Rich and tunable physicochemical properties make noble metal clusters promising candidates as novel nanomolecules for a variety of applications. Spectroelectrochemistry analysis is employed to resolve previously inaccessible electronic transitions in Au₁₃₀ clusters stabilized by a monolayer of di- and monothiolate ligands. Well-defined quantized double-layer charging of the Au core and oxidizable ligands make this Au₁₃₀ nanocluster unique among others and enable selective electrolysis to different core and ligand charge states. Subsequent analysis of the corresponding absorption changes reveals that different absorption bands originate from different electronic transitions involving both metal core energy states and ligand molecular orbitals. Besides the four discrete absorption bands in the steady-state UV–visible–near-IR absorption spectrum, additional transitions otherwise not detectable are resolved upon selective addition/removal of electrons at cores and ligand energy states, respectively, upon electrolysis. An energy diagram is proposed that successfully explains the major features observed in electrochemistry and absorption spectroscopy. Those assignments are believed applicable and effective to explain similar transitions observed in some other Au thiolate clusters

The Influence of Historical Socialism and Communism on the Shaping of a Society’s Economic Ethos: An Exploratory Study of Central and Eastern Europe

Morality of Profit-Making, Central and Eastern Europe, economic worldview, capitalism,