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Physics

Spectroscopy

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Displaying 551 - 575 of 927

Comparison of independently calculated ab-initio normal-mode displacements for the three C-H stretching vibrations of methanol along the internal rotation path

March 19, 2014
Author(s)
Li-Hong Xu, Ronald M. Lees, Jon T. Hougen, Joel M. Bowman, Xinchuan Huang, Stuart Carter
Comparison of graphical displays of normal-mode coefficients from recent quantum chemical projected-frequency calculations with analogous displays constructed after reexamination of results from more extensive higher-level calculations described earlier in

Optical self-focusing effect in coherent light scattering with condensates

March 3, 2014
Author(s)
Lu Deng, Edward W. Hagley, C.J. Zhu, G.X. Huang
We present a theoretical investigation of optical self-focusing effects in light scattering with condensates. Using long (>200 μs), red-detuned pulses we show numerically that a nonnegligible self-focusing effect is present that causes rapid optical beam

Dependence of Soot Optical Properties on Particle Morphology: Measurements and Model Comparisons

February 18, 2014
Author(s)
James Radney, Rian You, Xiaofei Ma, Joseph Conny, Michael R. Zachariah, Joseph T. Hodges, Christopher D. Zangmeister
We measure the mass-specific absorption and extinction cross sections for laboratory-generated soot aerosols. Two soot morphologies are investigated, both comprising fractal aggregates of nearly spherical monomers. The first type consists of monomer chains

Measuring order in regioregular poly(3-hexylthiophene) with solid-state 13C CPMAS NMR

January 10, 2014
Author(s)
Ryan C. Nieuwendaal, Chad R. Snyder, Dean M. DeLongchamp
We report on details of molecular packing in high molar mass poly(3-hexylthiophene) (P3HT) by solid-state 13C {1H} cross-polarization magic angle spinning (CPMAS) NMR measurements. The degree of polymer order was estimated for two films of varied drying

Probing the intracellular glutathione redox potential using in-cell NMR spectroscopy

January 2, 2014
Author(s)
Steve Y. Rhieu, Aaron A. Urbas, Daniel W. Bearden, John P. Marino, Vytautas Reipa, Katrice A. Lippa
Non-invasive and real-time analysis of cellular redox processes has been greatly hampered by lack of suitable measurement techniques. Here we describe an in-cell nuclear magnetic resonance (NMR)-based method for measuring the intracellular glutathione

Nonlinear Vibrational Spectrometry

December 31, 2013
Author(s)
Lee J. Richter
Second order nonlinear spectroscopies such as sum frequency generation (SFG) are intrinsically interface sensitive and enable sub monolayer sensitivity to be achieved at buried, optically accessible interfaces. Vibrationally-resonant SFG allows bond

Thermal Conductivity of Monolayer MoS2 Obtained from Temperature-Dependent Raman Spectroscopy

December 30, 2013
Author(s)
Rusen Yan, Jeffrey R. Simpson, Simone Bertolazzi, Jacopo Brivio, Michael Watson, Xufei Wu, Andras Kis, Tengfei Luo, Angela R. Hight Walker, Huili G. Xing
Atomically thin molybdenum disulphide (MoS2) is emerging as a potential alternative to graphene due to presence of bandgap, which is particularly advantageous to optoelectronic applications. The temperature-dependent Raman spectra of exfoliated monolayer

Novel structural features in Candida albicans hyphal glucan provide a basis for differential innate immune recognition of hyphae versus yeast

December 16, 2013
Author(s)
Dan Bearden, Douglas W. Lowman, Rachel R. Greene, Michael D. Kruppa, Max Pottier, Mario Monteiro, David L. Williams
The innate immune system differentially recognizes Candida albicans yeast and hyphae. It is not clear how the innate immune system effectively discriminates between yeast and hyphal forms of C. albicans. Glucans are major components of the fungal cell wall

ENVIRONMENTAL METABOLOMICS: NMR TECHNIQUES

December 8, 2013
Author(s)
Myrna Simpson, Dan Bearden
Environmental metabolomics is a rapidly growing area of research, and over the last decade the focus has been on organism responses to various types of environmental stressors (pollutants, nutritional shifts, and global climate change, for example)

Capture and isolation of highly-charged ions in a compact Penning trap: V12

December 4, 2013
Author(s)
Samuel Brewer, Nicholas D. Guise, Joseph Tan
Room-temperature, compact Penning traps have been shown recently to be useful for capture and storage of highly-charged ions extracted from an EBIT ion source at the National Institute of Standards and Technology (NIST). Highly-charged argon and neon ions

Electro-Thermo-Mechanical Model for Bulk Acoustic Wave Resonators

November 30, 2013
Author(s)
Eduard Rocas, Juan C. Collado Gomez, Jordi Mateu, Nathan D. Orloff, James C. Booth, Robert Aigner
We present the electro-thermo-mechanical constitutive relations, expanded up to the third order, for a BAW resonator. The relations obtained are implemented into a circuit model, which is validated with extensive linear and nonlinear measurements. The

Absolute line intensities for oxirane from 1420 to 1560 cm-1

November 15, 2013
Author(s)
F K. Tchana, M. Ngom, Agnes Perrin, Jean-Marie Flaud, Walter J. Lafferty, S. A. Ndiaye, El. A. Ngum
Absolute individual line intensities of numerous transitions of the fundamental ν2 and ν10 bands of oxirane (ethylene oxide, c-C2H4O) have been measured in the 1420-1560 cm-1 region using seven high- resolution Fourier transform spectra recorded at 0.002

Absolute line intensities for the nu3 band of oxirane (C2H4O)

November 15, 2013
Author(s)
Walter J. Lafferty, Jean-Marie Flaud, Fridolin Kwabia, A. Perrin, M. Ngom
Seven Fourier transform spectra of the ν3 band of oxirane (ethylene oxide) have been recorded with different pressures and used to derive individual line intensities. These line intensities were satisfactorily fit leading to accurate transition moment

High resolution gamma-ray spectroscopy with a microwave-multiplexed TES array

November 11, 2013
Author(s)
Omid Noroozian, John A. Mates, Douglas A. Bennett, Justus A. Brevik, Joseph W. Fowler, Jiansong Gao, Robert D. Horansky, Kent D. Irwin, Daniel R. Schmidt, Joel N. Ullom, Zhao Kang
We demonstrate the first gamma-ray spectroscopy with a microwave-multiplexed two-pixel TES(transition-edge sensor) array. We measured a $^{153}$Gd photon source and achieved an energy resolution of 63 eV full-width-at-half-maximum (FWHM) at 97 keV and an

Spectral line shapes investigation with Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectroscopy

October 23, 2013
Author(s)
A. Cygan, S. Wojtewicz, J. Domyslawska, Piotr Maslowski, Katarzyna E. Bielska, M. Piwinski, K. Stec, R.S. Trawinski, F Ozimek, C. Radzewicz, Hisashi Abe, T. Ido, Joseph T. Hodges, D Lisak, R. Ciurylo
A review of recent experiments involving a newly developed Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectroscopy (PDH-locked FS-CRDS) system is presented. By comparison to standard FS-CRDS, the PDH lock of the probe laser to the ring

Time-Resolved Infrared Studies of a Trimethylphosphine Model Derivative of [FeFe]-Hydrogenase

October 1, 2013
Author(s)
Edwin J. Heilweil, Christopher J. Stromberg, Melissa Johnson, James Thuman, Roger G. Letterman, Webster E. Charles
Model compounds that structurally mimic the hydrogen-producing active site of [FeFe] hydrogenases have been explored. In order to explore potential ground-state electronic structure effects on reaction mechanisms compared to hexacarbonyl derivatives, the

Rapid scan absorption spectroscopy using a waveform-driven electro-optic phase modulator in the 1.6- 1.65 ym region

September 25, 2013
Author(s)
Kevin O. Douglass, Stephen Maxwell, Gar W. Truong, Roger D. van Zee, Joseph T. Hodges, David Long, David F. Plusquellic
A method is reported for performing fast optical frequency scans over a bandwidth of 36.9 GHz and at a sweep rate of 40 kHz using a single second-order sideband from an electro-optic phase modulator driven by an arbitrary waveform generator. Single

A Missing Link in the Cascade Formation of High Symmetry Fullerene Cages

September 15, 2013
Author(s)
Dan Bearden, Jianyuan Zhang, Harry C. Dorn
Before the discovery of graphene, many versions of a “bottom-up” fullerene formation mechanism had been advanced starting with carbide (C2) that forms small carbon cluster chains and rings. However, in recent years evidence is emerging suggesting a “top
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