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Content tagged with: Diffraction and Scattering
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New Measuring Techniques Can Improve Efficiency, Safety of Nanoparticles

Mar. 2012- Eugene, OR | February 28th, 2012Using high-precision microscopy and X-ray scattering techniques, University of Oregon researchers have gained eye-opening insights into the process of applying green chemistry to nanotechnology that results in high yields, improves efficiency and dramatically reduces waste and potential negative exposure to human health or the environment. University of Oregon ...

Hacking the SEM: Crystal Phase Detection for Nanoscale Samples

Jan. 2012- Custom modifications of equipment are an honored tradition of the research lab. In a recent paper,* two materials scientists at the National Institute of Standards and Technology (NIST) describe how a relatively simple mod of a standard scanning electron microscope (SEM) enables a roughly 10-fold improvement in its ability to measure the crystal structure of nanoparticles and extremely thin ...

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Analysis of light scattering from human breast tissue using a custom dual-optical scanning near-field optical microscope

In this paper we introduce a custom scanning near-field optical microscope (SNOM) that simultaneously collects reflection and transmission near-field images along with topography. This dual-optical SNOM uses a bent probe, which allows for axial reflection imaging, accurate surface scanning, and easy identification of topographic artifacts. Using this novel dual-optical SNOM, we image desiccated ...

Atomic force microscopy based, multiphoton, photoelectron emission imaging

Images of photoelectron emission from metallic surfaces were obtained with a modified atomic force microscope operating in air. Illumination of the samples was achieved in the near field of a metal-coated microcantilever tip, placed in the beam of a femtosecond pulsed laser that is incident at a grazing angle with respect to the sample surface. Photoelectron currents were measured through the tip ...

Enhanced backward scattering by surface plasmons on silver film

Surface plasmon and its potential application in nanotechnology have attracted a remarkable amount of attention recently due to their novel properties. In this work we present an angularly resolved surface plasmon scattering study on a primitive metal surface. Using a reversed attenuated total reflection (RATR) setup in the experiment, we obtained a double-crescent shaped and enhanced scattering ...

Far-Field Optical Hyperlens Magnifying Sub-Diffraction-Limited Objects

The diffraction limit of light, which is causd by the loss of evanescent waves in the far field that carry high spatial frequency information, limits the resolution of optical lenses to the order of the wavelength of light. We report experimental demonstration of the optical hyperlens for sub-diffraction-limited imaging in the far field. The device magnifies subwavelength objects by transforming ...

Gel Point Determination of Biopolymer Based Semi-IPN Hydrogels

Water-based semi-IPNs (Interpenetrating Polymer Networks) were prepared by mixing two biopolymers, alginate and hydrophobically modified ethylhydroxy ethyl cellulose (HMEHEC), followed by crosslinking the alginate by in-situ release of calcium ions. By altering two different parameters, molecular weight of HMEHEC and calcium crosslinker concentration, we were able to fine tune the rheological ...

Ion-Complexation-Induced Changes in the Interaction Parameter and the Chain Conformation of PS-b-PMMA Copolymers

Small-angle neutron scattering (SANS) was used to study the changes of segmental interactions and chain conformation due to the formation of lithium?PMMA complexes in polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) copolymers as a function of temperature and the percentage of carbonyl groups coordinated with lithium ions. ?effc and statistical segmental length, ?, are derived from the ...

Macroscopic Arrays of Block Copolymers with Areal Densities of 10 Terbit/inch2 and Beyond

BCP self-assemble into a range of highly-ordered morphologies and by controlling the orientation and lateral ordering of the nanoscopic microdomains, numerous applications will emerge. By combining the bottom-up self-assembly of BCPs with top-down micro-fabrication processes faster, better and cheaper devices can be generated in very simple, yet robust, ways. By combining confinement effects ...

Nanoparticle-Reinforced Associative Network Hydrogels

ABA triblock copolymers in solvents selective for the midblock are known to form associative micellar gels. We have modified the structure and rheology of ABA triblock copolymer gels comprising poly(lactide)?poly(ethylene oxide)?poly(lactide) (PLA?PEO?PLA) through addition of a clay nanoparticle, laponite. Addition of laponite particles resulted in additional junction points in the gel via ...

Near-field Moir effect mediated by surface plasmon polariton excitation

We have demonstrated a surface plasmon polariton mediated optical Moir effect by inserting a silver slab between two subwavelength gratings. Enhancement of the evanescent fields by the surface plasmon excitations on the silver slab leads to a remarkable contrast improvement in the Moir fringes from two subwavelength gratings. Numerical calculations, which agree very well with the experimental ...

Raman Enhancement Factor of a Single Tunable Nanoplasmonic Resonator

We have developed a novel technique to precisely determine the Raman enhancement factor in single nanoplasmonic resonators (TNPRs). TNPRs are lithographically defined metallodielectric nanoparticles composed of two silver disks stacked vertically, separated by a silica layer. At resonance, the local electromagnetic fields are enhanced at the TNPR surface, making it an ideal surface-enhanced Raman ...

Semiclassical model of stimulated Raman scattering in photonic crystals

We study the stimulated Raman scattering (SRS) of light from an atomic system embedded in a photonic crystal and coherently pumped by a laser field. In our study, the electromagnetic field is treated classically and the atomic system is described quantum mechanically. Considering a decomposition of the pump and Stokes fields into the Bloch modes of the photonic crystals and using a multiscale ...

Structural Characterization of PLA?PEO?PLA Solutions and Hydrogels: Crystalline vs Amorphous PLA Domains

We have shown that we can significantly modify the nanoscale structure of solution and gels of ABA triblock copolymers in a solvent selective for the mid B block by making simple changes to the stereochemistry of the A block. We have also shown that the length of the A block can be used as an additional variable to further modify and thereby control the sizes of the nanoscale domains formed by ...

Two-Dimensional Imaging by Far-Field Superlens at Visible Wavelengths

We report that two-dimensional (2D) sub-diffraction-limited images can be theoretically reconstructed by a new metamaterial far-field superlens. The metamaterial far-field superlens, composed of a metal?dielectric multilayer and a one-dimensional (1D) subwavelength grating, can work over a broad range of visible wavelengths intrinsically. The imaging principle and the reconstruction process are ...

Well-Ordered Polymer Melts with 5 nm Lamellar Domains from Blends of a Disordered Block Copolymer and a Selectively Associating Homopolymer of Low or High Molar Mass

The use of short chain block copolymer melts as nanostructured templates with sub-10 nm domains is often limited by their low segregation strength (?N). Since increasing molar mass to strengthen segregation also increases the interdomain spacing of block copolymer melts, it is more desirable to increase the Flory?Huggins segment?segment interaction parameter, ?, to produce strong segregation. We ...

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Center for Nanoscale Science and Technology

Center for Nanoscale Science and Technology

National Institute of Standards and Technology
The NIST Center for Nanoscale Science and Technology (CNST) is a national user facility with a focus on commerce, supporting the U.S. nanotechnology enterprise from discovery to production by providing industry, academia, and other government agencies with access to world-class nanoscale measurement and fabrication methods and technology. The ...

Microtrac, Inc.

Microtrac, Inc.

Microtrac, the innovator of particle characterization technologies! Microtrac has been a pioneer in manufacturing light scattering particle size technology for over 35 years. In 1974 Microtrac released the world’s first commercially available particle size analyzer utilizing laser diffraction as a measurement method. Through a process of continuous innovation Microtrac has consistently ...

Oregon Nanoscience and Microtechnologies Institute

Oregon Nanoscience and Microtechnologies Institute

Oregon Signature Research Center
ONAMI is Oregon’s first ‘Signature Research Center’ and a multi-level collaboration among Oregon’s research universities, Pacific Northwest National Laboratory and industry in the “Silicon Forest” high-tech cluster that is home to the world’s leading semiconductor, MEMS, nanotechnology tools and ...

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Goran Karapetrov

Goran Karapetrov

Materials Science Division
Argonne National Laboratory

Ken Bosnick

Ken Bosnick

National Institute for Nanotechnology