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Full-Text Articles in Physics

Aberration Correction In Photoemission Microscopy And Applications In Photonics And Plasmonics, Rolf Könenkamp Sep 2017

Aberration Correction In Photoemission Microscopy And Applications In Photonics And Plasmonics, Rolf Könenkamp

Physics Faculty Publications and Presentations

We report on the design, assembly, operation and application of an aberration-corrected photoemission electron microscope. The instrument used novel hyperbolic mirror-correctors with two and three electrodes that allowed simultaneous correction of spherical and chromatic aberrations. A spatial resolution of 5.4nm was obtained with this instrument in 2009, and 4.7nm in subsequent years. New imaging methodology was introduced involving interferometric imaging of light diffraction. This methodology was applied in nano-photonics and in the characterization of surface-plasmon polaritons. Photonic crystals and waveguides, optical antennas and new plasmonic devices such as routers, localizers and filters were designed and demonstrated using the ...


Structural Identification Of Cubic Iron-Oxide Nanocrystal Mixtures: X-Ray Powder Diffraction Versus Quasi-Kinematic Transmission Electron Microscopy, Peter Moeck Mar 2008

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 Nov 2006

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 ...


Nonlocal Effects On Optical And Molecular Interactions With Metallic Nanoshells, P.T. Leung, Railing Chang Mar 2006

Nonlocal Effects On Optical And Molecular Interactions With Metallic Nanoshells, P.T. Leung, Railing Chang

Physics Faculty Publications and Presentations

Theoretical studies of the optical response of metallic nanoshells have been carried out, where quantum effects are partially accounted for through the application of a nonlocal response model for shells of mesoscopic dimensions. Both far field and near field interactions are considered, with the incident source being a plane wave and an emitting molecular dipole, respectively. It is found that these nonlocal effects can lead to significant deviations from macroscopic electrodynamic theory, for shells of ultrasmall dimensions (<10 >nm) or ultrathin thickness (~1 nm), and are particularly significant for processes involving higher multipolar responses of the nanoshells. It is further concluded ...


Making Sense Of Nanocrystal Lattice Fringes, P. Fraundorf, Wentao Qin, Peter Moeck, Eric Mandell Jan 2005

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 ...


Photodeflection Probing Of The Explosion Of A Liquid Film In Contact With A Solid Heated By Pulsed Excimer Laser Irradiation, P.T. Leung, Nhan Do, Leander Klees, Andrew C. Tam, Wing P. Leung Apr 1993

Photodeflection Probing Of The Explosion Of A Liquid Film In Contact With A Solid Heated By Pulsed Excimer Laser Irradiation, P.T. Leung, Nhan Do, Leander Klees, Andrew C. Tam, Wing P. Leung

Physics Faculty Publications and Presentations

The explosion or rapid vaporization of a liquid film on an opaque surface by a pulsed laser is studied experimentally. Using a probe-beam deflection sensing (PDS) scheme, together with a previously developed transmission monitor, the distortion of the PDS signal due to the generation of shock waves by the exploding liquid is investigated. Various liquids, including alcohols and pure water in contact with substrates such as polyimide, amorphous carbon, and silicon, are studied for a wide range of excimer laser fluences. It is concluded that the present PDS technique is highly sensitive to the explosion threshold.


Decay Of Molecules At Corrugated Thin Metal Films, P.T. Leung, Young Sik Kim, Thomas F. George May 1989

Decay Of Molecules At Corrugated Thin Metal Films, P.T. Leung, Young Sik Kim, Thomas F. George

Physics Faculty Publications and Presentations

The problem of the decay rate for molecules at corrugated thin metal films is considered theoretically via a classical phenomenological approach by generalization of a previous theory for a single rough surface. In particular, numerical results are worked out in detail for grating films with various possible arrangements of the two grating surfaces, and for both cases with a supported and a free-standing film. Effects due to cross coupling into the long- and short-range surface plasmons are observed, and correlations to recent experiments performed by Gruhlke, Holland, and Hall are made. It is suggested that fluorescence experiments with pulsed-laser excitations ...