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You searched on: Author: angela hight walker

Displaying records 11 to 20 of 78 records.
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11. Preferential Outward Diffusion of Cu during Unconventional Galvanic Replacement Reactions between HAuCl4 and Surface-limited Cu Nanocrystals
Published: 8/25/2011
Authors: Yonglin Liu, Angela R Hight Walker
Abstract: Using pre-synthesized Cu-Cu1.81S hetero-oligomer and Cu-Cu2S heterodimer NCs as templates and reactants, the addition of HAuCl4 leads to the preferential outward diffusion of Cu, evidenced by the formation of straight or kinked CuAu nanowires, respec ...

12. Evolution of Microscopic Localization in Graphene in a Magnetic Field: From Scattering Resonances to Quantum Dots.
Published: 1/9/2011
Authors: Suyong S. Jung, Gregory M. Rutter, Nikolai Nikolayevich Klimov, David B Newell, Irene G. Calizo, Angela R Hight Walker, Nikolai B Zhitenev, Joseph A Stroscio
Abstract: Graphene is a unique material displaying high-mobility transport in monolayer-thin films. However, its properties are strongly dependent on interactions with substrates, local charges and environment. Scanned probe microscopies can be used to local ...

13. Monodisperse Gold-Copper bimetallic Nanocubes: Facile One-Step Synthesis with Controllable Sizes and Compositions
Published: 8/16/2010
Authors: Yonglin Liu, Angela R Hight Walker
Abstract: We demonstrate a one-pot polyol strategy for the synthesis of Au - Cu perfect nanocubes. To the best of the authors knowledge, this represents the first-time production of Au - Cu bimetallic nanocubes. By carefully adjusting the reaction parameter ...

14. Separation and Characterization of Double Wall Carbon Nanotube Sub-Populations
Published: 7/8/2010
Authors: JiYeon Huh, Angela R Hight Walker, Hyun Wook Ro, Jan Obrzut, Jeffrey A Fagan
Abstract: We present the separation of surfactant encapsulated double wall carbon nanotubes (DWCNTs) synthesized by the high pressure carbon monoxide decomposition (HiPco) process by length and electronic characteristics using density gradient ultracentrifugat ...

15. Facile One-Pot Synthesis of Metal-Semiconductor Hybrid Nanocrystals via Chemical Transformation: The Case of Cu-CuxS Heterodimers and Hetero-Oligomers
Published: 3/18/2010
Authors: Yonglin Liu, Angela R Hight Walker
Abstract: Metal-semiconductor hybrid nanocrystals (HNCs) hold great potential in the fields of photocatalysis, biomedical imaging, and anticancer nanomedicine. However, their chemical synthetic procedures remain complex and challenging. Here, we apply chemical ...

16. Sample Preparation Protocols for Realization of Reproducible Characterization of Single-walled Carbon Nanotubes
Published: 12/1/2009
Authors: Angela R Hight Walker, Jeffrey A Fagan, Stephanie A Hooker, Michael T Postek, Stephen A Wise, Andras Vladar, Rolf Louis Zeisler
Abstract: Harmonized sample pre-treatment is an integral first step in ensuring metrological quality of measurements as regards repeatability, inter-laboratory reproducibility and commutability. The development of standard preparation methods for SWCNT sample ...

17. The effect of dispersant on defects in length-separated single-wall carbon nanotubes measured by Raman spectroscopy
Published: 11/1/2009
Authors: Jeffrey Ray Simpson, Jeffrey A Fagan, Matthew Becker, Erik K. Hobbie, Angela R Hight Walker
Abstract: The fluorescence quantum yield of single-wall carbon nanotubes (SWCNTs) in solution depends dramatically on dispersant. To evaluate the role of defects in this dependence, we compare Raman spectra from aqueous suspensions of SWCNTs dispersed using ei ...

18. Multimodal, Nanoscale, Hyperspectral Imaging Demonstrated on Heterostructures of Quantum Dots and DNA-Wrapped Single-Wall Carbon Nanotubes
Published: 10/21/2009
Authors: Hyeong Gon (Hyeonggon) Kang, Matthew Lawrence Clarke, Jianyong Tang, John Taylor Woodward IV, Shin G. Chou, Zhenping Zhou, Angela R Hight Walker, Tinh Nguyen, Jeeseong Hwang
Abstract: A multimodality imaging technique integrating atomic force, polarized Raman, and fluorescence lifetime microscopy and a 2D autocorrelation image analysis is applied to study the properties of a mesoscopic heterostucture of nanoscale materials. This ...

19. Probing the Growth and Aging of Colloidal Cobalt Nanoparticles
Published: 6/11/2009
Authors: Guangjun Cheng, Cindi L. Dennis, Robert D Shull, Angela R Hight Walker
Abstract: We have combined transmission electron microscopy (TEM) and magnetic measurements to characterize the growth of colloidal cobalt (Co) nanoparticles during synthesis and their subsequent stability in air. During the growth, TEM measurements have shown ...

20. Dipolar Chains formed by synthesized cobalt nanocubes
Published: 5/11/2009
Authors: Guangjun Cheng, Robert D Shull, Angela R Hight Walker
Abstract: Cobalt nanocubes with an average edge length of 50 nm and the epsilon crystalline structure were synthesized via thermo-decomposition in 1,2-dichlorobenzene at 120 oC in the presence of the surfactants. These nanocubes form dipolar chains upon drying ...

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