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Full-Text Articles in Nanoscience and Nanotechnology
Metamaterial Devices For The Terahertz Band, Gabriel Paul Kniffin
Metamaterial Devices For The Terahertz Band, Gabriel Paul Kniffin
Center for Electron Microscopy and Nanofabrication Publications and Presentations
Terahertz (THz) and metamaterials are both hot topics in electromagnetics research. The THz band (0.1-10 THz) lies in the ‘gap’ between microwave and far infrared regions. Research is currently underway to characterize how these waves interact with matter, with potential applications including security screening, medical imaging, and non-destructive evaluation. Metamaterials are artificial materials containing sub-wavelength structures whose material properties, μ and ǫ can be ‘tuned’ to desired specifications, including simultaneously negative values, resulting in exotic properties such as a negative refractive index. Current metamaterials research includes the design of devices that operate at THz frequencies, filling a niche left wide …
Structural Identification Of Cubic Iron-Oxide Nanocrystal Mixtures: X-Ray Powder Diffraction Versus Quasi-Kinematic Transmission Electron Microscopy, Peter Moeck
Physics Faculty Publications and Presentations
Two novel (and proprietary) strategies for the structural identification of a nanocrystal from either a single high-resolution (HR) transmission electron microscopy (TEM) image or a single precession electron diffraction pattern are proposed and their advantages discussed in comparison to structural fingerprinting from powder X-ray diffraction patterns. Simulations for cubic magnetite and maghemite nanocrystals are used as examples.
Transmission Electron Goniometry And Its Relation To Electron Tomography For Materials Science Apoplications, Peter Moeck, P. Fraundorf
Transmission Electron Goniometry And Its Relation To Electron Tomography For Materials Science Apoplications, Peter Moeck, P. Fraundorf
Physics Faculty Publications and Presentations
Aspects of transmission electron goniometry are discussed. Combined with high resolution phase contrast transmission electron microscopy (HRTEM) and atomic resolution scanning TEM (STEM) in the atomic number contrast (Z-STEM) or the phase contrast bright field mode, transmission electron goniometry offers the opportunity to develop dedicated methods for the crystallographic characterization of nanocrystals in three dimensions. The relationship between transmission electron goniometry and electron tomography for materials science applications is briefly discussed. Internet based java applets that facilitate the application of transmission electron goniometry for cubic crystals with calibrated tilt-rotation and double-tilt specimen holders/goniometers are mentioned. The so called cubic-minimalistic tilt …
Making Sense Of Nanocrystal Lattice Fringes, P. Fraundorf, Wentao Qin, Peter Moeck, Eric Mandell
Making Sense Of Nanocrystal Lattice Fringes, P. Fraundorf, Wentao Qin, Peter Moeck, Eric Mandell
Physics Faculty Publications and Presentations
The orientation dependence of thin-crystal lattice fringes can be gracefully quantified using fringe-visibility maps, a direct-space analog of Kikuchi maps [Nishikawa and Kikuchi, Nature (London) 121, 1019 (1928)]. As in navigation of reciprocal space with the aid of Kikuchi lines, fringe-visibility maps facilitate acquisition of crystallographic information from lattice images. In particular, these maps can help researchers to determine the three-dimensional lattice of individual nanocrystals, to 'fringe-fingerprint' collections of randomly oriented particles, and to measure local specimen thickness with only a modest tilt. Since the number of fringes in an image increases with maximum spatial-frequency squared, these strategies (with help …