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Physics

Spectroscopy

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Displaying 376 - 400 of 911

Approaches for Characterizing Nonlinear Mixtures in Hyperspectral Imagery

June 21, 2017
Author(s)
Robert S. Rand, Ronald G. Resmini, David W. Allen
This study considers a physics-based and a kernel-based approach for characterizing pixels in a scene that may be linear (areal mixed) or nonlinear (intimately mixed). The physics-based method is based on earlier studies that indicate nonlinear mixtures in

Tip Enhanced Raman Scattering of Graphene

June 20, 2017
Author(s)
Ryan Beams
This article reviews the mechanism of tip enhanced Raman spectroscopy (TERS) and its importance for characterizing graphene. The theoretical foundation of TERS and experimental implementation are discussed. Conventionally, Raman scattering is treated as a

A pulsed scalar optically-pumped magnetometer

June 16, 2017
Author(s)
Vladislav P. Gerginov, Sean P. Krzyzewski, Svenja A. Knappe
A scalar magnetic field sensor based on 87Rb vapor millimeter-size cell is described. The magnetometer uses co-propagating pump/probe laser beam, amplitude modulation of the pump beam and non-demolition polarization rotation detection of the probe beam

Metabolomics Analysis of Effects of Commercial Soy-based Protein Products in Red Drum (Sciaenops ocellatus)

June 14, 2017
Author(s)
Fabio Casu, Aaron Watson, Justin Yost, John Leffler, Gibson Gaylord, Frederic Barrows, Paul A. Sandifer, Dan Bearden, Michael R. Denson
In this study we investigated the metabolic effects of four different commercial soy-based protein products on red drum (Sciaenops ocellatus) using NMR-based metabolomics along with unsupervised principal component analysis (PCA) to evaluate metabolic

Morphological characterization of fullerene and fullerene-free organic photovoltaics by combined real and reciprocal space techniques

May 26, 2017
Author(s)
Donglin Zhao, Qinghe Wu, Luping Yu, Harald Ade, Dean DeLongchamp, Lee J. Richter, Subhrangsu Mukherjee, Andrew Herzing
Morphology can play a critical role in determining function in organic photovoltaic (OPV) systems. Recently molecular acceptors have showed promise to replace¬ fullerene derivatives as acceptor materials in bulk heterojunction solar cells and have achieved

CH3NH3PbI3 perovskites: Ferroelasticity revealed

April 14, 2017
Author(s)
Evgheni Strelcov, Qingfeng Dong, Tao Li, Jungseok Chae, Yuchuan Shao, Yehao Deng, Alexei Gruveman, Jinsong Huang, Andrea Centrone
Ferrolectricity has been proposed as a plausible meachanism to explain the high photovoltaic conversion efficiency in organic-inorganic perovskites; however, convincing experimental evidence in support to this hypothesis is still missing. Identifying and

Broadband spectral measurements of diffuse optical properties by an integrating sphere instrument at the National Institute of Standards and Technology

March 30, 2017
Author(s)
Paul Lemaillet, Jeeseong Hwang, Heidrun Wabnitz, Dirk Grosenick, Lin Yang, David W. Allen
Diffuse materials that approximate the optical properties of human tissue are commonly used as phantoms. In order to use the phantoms in a manner that provides consistent results relative to independent measurements, the optical properties need to be tied

Beating Darwin-Bragg losses in lab-based ultrafast x-ray experiments

March 24, 2017
Author(s)
Wilfred Fullagar, Jens Uhlig, Ujjwal Mandal, Dharma Kurunthu, Amal El Nahhas, Hideyuki Tatsuno, Alireza Honarfar, Fredrik Gustafsson, Villy Sundstrom, Mikko Palosaari, Luis Miaja Avila, Young I. Joe, Daniel Swetz, Joel Ullom
The use of low temperature thermal detectors for avoiding Darwin-Bragg losses in lab-based ultrafast experiments has begun. An outline of the background of this new development is offered, showing the relevant history and initiative taken by this work.

Efficient Simulation of Secondary Fluorescence via NIST DTSA-II Monte Carlo

March 17, 2017
Author(s)
Nicholas Ritchie
Secondary fluorescence, the final term in the familiar matrix correction triumvirate Z·A·F, is the most challenging for Monte Carlo models to simulate. In fact, only two implementations of Monte Carlo models commonly used to simulate electron probe x-ray

Electronic Structure of Single Crystal a-Perylene

March 16, 2017
Author(s)
Sujitra J. Pookpanratana, Katelyn Goetz, Ruslan Ovsyannikov, Erika Giangrisostomi, Emily G. Bittle, Oana Jurchescu, Steven W. Robey, Christina A. Hacker
In organic electronics, the highest estimated charge mobility in a device is typically achieved when the organic semiconductor is a single crystal. However, the measurement of the electronic and chemical structure of organic single crystals by

Liquid Chromatography Column Theory and Technology

March 8, 2017
Author(s)
Lane C. Sander
Column selection is probably the single most important aspect of method development that will directly affect measurement accuracy and precision of liquid chromatographic (LC) measurements. An understanding of physical and chemical properties of LC columns

Characterization of a PXIe based low-field digital NMR spectrometer

February 25, 2017
Author(s)
Joshua R. Biller, Karl F. Stupic, Anthony B. Kos, Timothy Weilert, George Rinard, Yoshi Nakashima, John M. Moreland
A low-field nuclear magnetic resonance (NMR) instrument is an important tool for investigating a wide variety of samples under different conditions. In this paper, we describe a system constructed primarily with commercially available hardware and control

The Cu II Spectrum

February 24, 2017
Author(s)
Alexander Kramida, Gillian Nave, Joseph Reader
New wavelength measurements in the vacuum ultraviolet (VUV), ultraviolet and visible spectral regions have been combined with available literature data to refine and extend the description of the spectrum of singly ionized copper (Cu II). In the VUV region

Incomplete reactions in nanothermite composites

February 3, 2017
Author(s)
Rohit J. Jacob, Diana Ortiz-Montalvo, Kyle R. Overdeep, Timothy P. Weihs, Michael R. Zachariah
Exothermic reactions between oxophilic metals and transition/ post transition metal-oxides have been well documented owing to their fast reaction time scales (10 μs). This article examines the extent of reaction in nano-aluminum based thermite systems

Comprehensive atomic wavelengths, energy levels and hyperfine structure for singly-ionized iron-group elements

January 23, 2017
Author(s)
Gillian Nave, Craig J. Sansonetti, Keeley I. Townley-Smith, J C. Pickering, Florence Liggins, Anne P. Thorne, Christian Clear
We summarize recent work at the National Institute of Standards and Technology and Imperial College London on wavelengths, hyperfi ne structure, energy levels, and analysis of singly-ionized iron-group elements of astrophysical interest.
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