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Physics

Spectroscopy

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Displaying 226 - 250 of 911

Localized Excitons in NbSe2-MoSe2 Heterostructures

July 8, 2020
Author(s)
Jaydeep Joshi, Tong Zhou, Sergiy Krylyuk, Albert Davydov, Igor Zutic, Patrick M. Vora
Neutral and charged excitons (trions) in atomically-thin materials offer important capabilities for photonics, from ultrafast photodetectors to highly-efficient lightemitting diodes and lasers. Recent studies of van der Waals (vdW) heterostructures

Measurements of the Linear Polarization of Satellite Transitions from Li- and Be- like Ar Ions

June 18, 2020
Author(s)
Amy Gall, Dipti Goyal, Sean W. Buechele, Samuel C. Sanders, Roshani Silwal, Csilla Szabo-Foster, N Brickhouse, Yuri Ralchenko, Endre A. Takacs
Non-thermal electron distributions, such as beams of electrons, are found in many laboratory and astrophysical plasma sources and can produce anisotropic and polarized emission. Theories used to model the emission require sublevel specific analysis, which

Determination of the isotopic change in nuclear charge radius from extreme-ultraviolet spectroscopy of highly charged ions of Xe

June 16, 2020
Author(s)
Yuri Ralchenko, Roshani Silwal, A. Lapierre, John Gillaspy, Joan M. Dreiling, S A. Blundell, Dipti Goyal, A. Borovik, Jr., G Gwinner, A.C.C. Villari, Endre Takacs
The electron beam ion trap (EBIT) at the National Institute of Standards and Technology was employed to measure the isotopic shift of the Na-like D 3s 2S1=2 3p 2P1=2;3=2, Mg-like 3s2 1S0 3s3p 1P1, Mg-like 3s2 1S0 3s3p 3P1, Al-like 3s23p 2P1=2 3s23p 2P3=2

Spectroscopic analysis of N-intrashell transitions in Rb-like to Ni-like Yb ions

June 9, 2020
Author(s)
Dipti Goyal, R. Silwal, Joan M. Dreiling, Samuel C. Sanders, Endre A. Takacs, Yuri Ralchenko
Extreme ultraviolet spectra of highly-charged ytterbium ions produced in an electron beam ion trap at National Institute of Standards and Technology were observed with a at- eld grazing incidence spectrometer in the wavelength region of about 4 nm to 20 nm

Mid-Infrared Dual Frequency Comb Spectroscopy for Combustion Analysisin the 2.8 to 5 micron Spectral Region

June 7, 2020
Author(s)
Ian Coddington, Nathan Newbury, Greg Rieker, Amanda S. Makowiecki, Daniel Herman, Nazanin Hoghooghi, Elizabeth F. Strong, Gabriel Ycas, Fabrizio Giorgetta, Ryan Cole, Caelan Lapointe, Jeff Glusman, John Daily, Peter E. Hamlington
We demonstrate the application of mode-locked mid-infrared dual frequency comb spectroscopy for combustion analysis. With two settings of the same dual-comb system, the measurement spans 1500 cm-1 (2.8 to 5 microns) with 0.0067 cm-1 (200 MHz) point spacing

Embracing Uncertainty: Modeling Uncertainty in EPMA - Part I

May 21, 2020
Author(s)
Nicholas Ritchie
This is the first in a series of articles which present a new framework for computing the uncertainty in electron excited X-ray microanalysis measurements. This article will discuss the framework and apply it to a handful of simple but useful sub

Infrared and Raman chemical imaging and spectroscopy at the nanoscale

May 19, 2020
Author(s)
Dmitry Kurouski, Alexandre Dazzi, Renato Zenobi, Andrea Centrone
The advent of nanotechnology, and the need to understand the chemical composition at the nanoscale, has stimulated the convergence of IR and Raman spectroscopy with scanning probe methods, resulting in new nanospectroscopy paradigms. Here we review two of

High-Q dark hyperbolic phonon-polaritons in hexagonal boron nitride nanostructures

May 18, 2020
Author(s)
Georg Ramer, Mohit Tuteja, Joseph R. Matson, Marcelo I. Davanco, Thomas G. Folland, Andrey Kretinin, Takashi Taniguchi, Kenji Watanabe, Kostya Novoselov, Joshua D. Caldwell, Andrea Centrone
The anisotropy of hexagonal boron nitride (hBN) crystals gives rise to hyperbolic phonon polaritons (HPhPs), notable for their volumetric frequency-dependent angular propagation and strong confinement. For frustum (truncated nanocone) structures, theory

Linear Polarization of Anisotropically Excited X-ray Lines from the n=2 Complex in He-like Ar16+

May 13, 2020
Author(s)
Dipti Goyal, Sean W. Buechele, Amy C. Gall, Samuel C. Sanders, Csilla I. Szabo-Foster, Roshani Silwal, Endre A. Takacs, Yuri Ralchenko
High-resolution x-ray spectra were recorded at the National Institute of Standards and Technology (NIST) electron beam ion trap (EBIT) using two Johann-type crystal spectrometers, with their dispersion planes oriented parallel and perpendicular to the beam

Enhanced magnetization in proton irradiated Mn3Si2Te6 van der Waals crystals

April 28, 2020
Author(s)
L. M. Martinez, H. Iturriaga, R. Olmos, L. Shao, Y. Liu, Thuc Mai, C. Petrovic, Angela R. Hight Walker, S. R. Singamaneni
van der Waals (vdW) engineering of magnetism is a topic of increasing research interest in the community at present. We study the magnetic properties of quasi-two-dimensional layered vdW Mn3Si2Te6 (MST) crystals upon proton irradiation as a function of

Radiation damage of liquid electrolyte during focused X-ray beam photoelectron spectroscopy

April 12, 2020
Author(s)
Christopher M. Arble, Hongxuan Gou, Evgheni Strelcov, Brian D. Hoskins, Patrick Zeller, Matteo Amati, Luca Gregoratti, Andrei A. Kolmakov
Ambient pressure X-ray photoelectron spectroscopy (APXPS) has become an effective tool to interrogate chemical states at surfaces relevant to real operational conditions. Herein we employ a graphene-capped microvolume array sample platform for scanning

Field Ion Emission in an Atom Probe Microscope Triggered by Femtosecond-Pulsed Coherent Extreme Ultraviolet Light

March 12, 2020
Author(s)
Ann C. Chiaramonti Debay, Luis Miaja Avila, Benjamin W. Caplins, Paul T. Blanchard, Norman A. Sanford, Brian Gorman, David R. Diercks
This paper reports construction of an extreme ultraviolet (EUV) radiation-triggered atom probe tomograph and describes the results from initial experiments on amorphous SiO2. Femtosecond-pulsed coherent EUV radiation of 29.6 nm wavelength (41.85 eV photon

Polarization Dependence of Charge Conduction in Conjugated Polymer Films Investigated with Time- Resolved Terahertz Spectroscopy

March 6, 2020
Author(s)
Timothy J. Magnanelli, Sebastian Engmann, Jared K. Wahlstrand, John C. Stephenson, Lee J. Richter, Edwin J. Heilweil
We interrogate polarization anisotropy associated with charge conduction in films of the block co polymer PCDTPT, consisting of alternating cyclopenta dithiophene (donor) and thiadiazolo pyridine (acceptor) units with respect to sample morphology. Film

Dielectronic resonances of LMn and LNn (? 4) series in highly-charged M-shell tungsten ions

March 4, 2020
Author(s)
Dipti Goyal, A. Borovik, Jr., R. Silwal, Joan M. Dreiling, Amy C. Gall, Endre Takacs, Yuri Ralchenko
We present accurate spectroscopic measurements and detailed theoretical analysis of inner-shell LM$n$ and LN$n$ ($n$ $\geq$ 4) dielectronic resonances (DR) in highly-charged M-shell ions of tungsten. The x-ray emission from W$^49+}$ through W$^64+}$ was

Optical evidence of the chiral magnetic anomaly in the Weyl semimetal TaAs

March 4, 2020
Author(s)
Antonio L. Levy, Andrei Sushkov, Fengguang Liu, Bing Shen, Ni Ni, Howard D. Drew, Gregory Jenkins
Chiral pumping from optical electric fields oscillating at THz frequencies is observed in the Weyl material TaAs with electric and magnetic fields aligned along both the a- and c-axes. Free carrier spectral weight enhancement is measured directly for the
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