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Physics

Spectroscopy

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Displaying 526 - 550 of 911

Multiheterodyne spectroscopy with optical frequency combs generated from a continuous-wave laser

May 1, 2014
Author(s)
David A. Long, Adam J. Fleisher, Kevin O. Douglass, Stephen E. Maxwell, Katarzyna E. Bielska, Joseph T. Hodges, David F. Plusquellic
Dual-drive Mach-Zehnder modulators were utilized to produce power-leveled optical frequency combs (OFCs) from a continuous-wave laser. The resulting OFCs contained up to fifty unique frequency components and spanned more than 200 GHz. Simple changes to the

Energy Levels And Spectral Lines Of Quadruply Ionized Iron (Fe V)

April 24, 2014
Author(s)
Alexander Kramida
This compilation revises and extends the previously recommended list of energy levels of quadruply ionized iron (Fe V) and provides a comprehensive list of observed spectral lines and transition probabilities in this spectrum. The new level optimization

Measurement of the Kr XVIII 3d 2D5/2 lifetime in a Unitary Penning Trap

April 24, 2014
Author(s)
Nicholas D. Guise, Joseph Tan, Samuel Brewer, Charlotte F. Fischer, P. Jonsson
The lifetime of the 3d 2D5/2 in the fine-structure doublet of the Kr XVIII ground configuration is measured using a compact Penning trap with 2.2 cm3 of trapping volume. Kr17+ ions produced in an electron beam ion trap (EBIT) are extracted and captured in

Time-resolved surface infrared spectroscopy during atomic layer deposition of TiO2 using tetrakis(dimethylamido)titanium and water

April 23, 2014
Author(s)
Brent A. Sperling, John Hoang, William A. Kimes, James E. Maslar, Kristen L. Steffens, Nhan V. Nguyen
Atomic layer deposition of titanium dioxide using tetrakis(dimethylamido)titanium (TDMAT) and water vapor is studied by reflection-absorption infrared spectroscopy (RAIRS) with a time resolution of 120 ms. Decomposition of the adsorbed TDMAT is observed

Isolated line shapes of molecular oxygen: ab initio calculations versus measurements

April 8, 2014
Author(s)
Vincent T. Sironneau, Joseph T. Hodges, Jean M. Hartmann, Julien Lamouroux
We present comparisons between measured isolated line shapes of molecular oxygen in air and those calculated, free of any adjusted parameter, using requantized Classical Molecular Dynamics Simulations (rCMDS). This work extends a previous study made for a

N-methylmesoporphyrin IX fluorescence as a reporter of strand orientation in guanine quadruplexes

April 1, 2014
Author(s)
Navin C. Sabharwal, Victoria Savikhin, Joshua Turek-Herman, John M. Nicoludis, Veronika Szalai, Liliya Yatsunyk
Guanine quadruplexes (GQ) are four-stranded DNA structures formed by guanine-rich DNA sequences. Formation of GQs inhibits cancer cell survival, but detecting GQs in vivo has proved difficult, in part because of GQ structural diversity. Development of GQ

Quantum-noise-limited cavity ring-down spectroscopy

March 29, 2014
Author(s)
David A. Long, Adam J. Fleisher, Szymon S. Wojtewicz, Joseph T. Hodges
Spectroscopic techniques with ultra-high sensitivity allow for the study of a wide variety of physical and chemical phenomena, ranging from the interrogation of individual atoms1 and molecules2,3 to the quantitative extraction of ensemble properties from

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
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