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Search Publications by: John Vinson (Fed)

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Displaying 26 - 42 of 42

Revealing Electronic Signature of Lattice Oxygen Redox in Lithium Ruthenates and Implications for High-Energy Li-ion Battery Material Designs

September 11, 2019
Author(s)
Yang Yu, Pinar Karayaylali, Stanislaw Nowak, Livia Giordano, Magali Gauthier, Wesley Hong, Ronghui Kuo, John Vinson, Dimosthenis Sokaras, Cheng-Jun Sun, Nenian Charles, Filippo Maglia, Roland Jung, Yang Shao-Horn
Anion redox in lithium transition metal oxides such as Li2RuO3 and Li2MnO3, has catalyzed intensive research efforts on the seek of first-row transition metal oxides that may boost up the energy density for lithium-ion batteries. The physical origin for

Resonant X-ray Emission and Valence-band Lifetime Broadening in LiNO3

August 28, 2019
Author(s)
John T. Vinson, Terrence J. Jach, Matthias Mueller, Rainer Unterumsberger, Burkhard Beckhoff
X-ray absorption and resonant inelastic x-ray scattering measurements are carried out on lithium nitrate LiNO3. Echoing previous studies on ammonium nitrate, the σ orbitals around the nitrogen atoms exhibit a large lifetime effect. Experimentally, this is

Probing the Participation of Oxygen Redox in the Electrochemical Cycling of Li-Rich Li2IrO3

March 25, 2019
Author(s)
Eric L. Shirley, John T. Vinson, Liang Li, Maria K. Chan, Joong S. Park, Eungje Lee, John W. Freeland, Zhenpeng Yao, Fernando Castro, Timothy T. Fister, Christopher M. Wolverton, Michael Thackeray
To exploit extra capacity beyond the traditionally postulated transition metal redox in Li-ion batteries, it is imperative to understand the exact role of oxygen in the charge compensation, i.e., what triggers the electron occupation change in oxygen and

Identification of dopant site and its effect on electrochemical activity in Mn-doped Lithium Titanate

December 20, 2018
Author(s)
Harischchandra Singh, Mehmet Topsakal, Klaus Attenkofer, Tamar Wolf, Michal Leskes, Yandong Duan, Feng Wang, John Vinson, Deyu Lu, Anatoly Frenkel
We observed significant battery rate performance drop of nearly 20% in 1% Mn doped Lithium Titanate (LTO) compared to the pristine LTO. Using a combination of the X-ray absorption near edge structure experiment with theoretical modeling we demonstrated

Spectroscopic Signature of the Oxygen States in Peroxides

October 16, 2018
Author(s)
Zengqing Zhuo, Chaitanya D. Pemmaraju, John Vinson, Chunjing Jia, Brian Moritz, Ilkyu Lee, Shawn Sallies, Qinghao Li, Jinpeng Wu, Kehua Dai, Yi-De Chuang, Zahid Hussain, Feng Pan, Thomas P. Devereaux, Wanli Yang
Recent debates on the nonconventional oxygen behaviors in electrochemical devices have triggered a pressing demand of a reliable detection and understanding of non-divalent oxygen states beyond conventional oxygen absorption spectroscopy. Here, enabled by

Imaging catalytic CO2 reduction on Cu2O (110) -- A First-Principles study

March 5, 2018
Author(s)
Eric L. Shirley, John T. Vinson, Liang Li, Maria K. Chan, Jeffry Greeley, Jeffrey R. Guest, Rui Zhang
Balancing global energy needs against increasing greenhouse gas emissions requires new methods for efficient CO2 reduction. While photoreduction of CO2 is promising, the rational design of photocatalysts hinges on precise characterization of the surface

Intrinsic Orbital Angular Momentum States of Neutrons

March 2, 2018
Author(s)
Ronald L. Cappelletti, Terrence J Jach, John T. Vinson
A recent neutron interferometry experiment attempted to observe the orbital angular momentum (OAM) of neutron de Broglie waves of neutron de Broglie waves using a spiral phase (SPP) (Nature 525, 504 (2015) [1]). Based upon conventional neutron optical

Resonant X-ray Emission of Hexagonal Boron Nitride

November 9, 2017
Author(s)
John T. Vinson, Terrence J Jach, Matthias Mueller, Rainer Unterumsberger, Burkhard Beckhoff
The electronic structure of hexagonal boron nitride ({\it h}-BN) is explored using measurements of x-ray absorption and resonant inelastic x-ray scattering (RIXS) at the nitrogen K edge (1{\it s}) in tandem with calculations of the same using many-body

Temperature and Radiation Effects at the Fluorine K-edge in LiF

May 30, 2017
Author(s)
Craig P. Schwartz, Francisco Ponce, Stephan Friedrich, Stephen P. Cramer, John Vinson, David Prendergast
The F K-edge of LiF is studied both experimentally and theoretically as a function of temperature. Instantaneous thermal fluctuations in atomic positions are shown in molecular dynamics simulations to increase in amplitude from 0.029 - 0.064 Å in the

Accurate X-Ray Spectral Predictions: An Advanced Self-Consistent-Field Approach Inspired by Many-Body Perturbation Theory

March 2, 2017
Author(s)
Yufeng Liang, John Vinson, Chaitanya D. Pemmaraju, Walter Drisdell, Eric L. Shirley, David Prendergast
The self-consistent-field method and the many-body approach are two cornerstones for obtaining electronic excitations from first- principles. Using the two distinct theories, we study the O 1s core excitations that have become increasingly important for

Enabling photoemission electron microscopy in liquids via graphene-capped microchannel arrays

February 8, 2017
Author(s)
Hongxuan Guo, Evgheni Strelcov, Alexander Yulaev, Jian Wang, Narayana Appathurai, Stephen Urquhart, John Vinson, Subin Sahu, Michael P. Zwolak, Andrei Kolmakov
Photoelectron emission microscopy (PEEM) is a powerful tool to spectroscopically access dynamic surface processes at the nanoscale but is traditionally limited to ultra-high or moderate vacuum conditions. Here, we develop a novel graphene-capped

Quasiparticle Lifetime Broadening in Resonant X-ray Scattering of Ammonium Nitrate

July 28, 2016
Author(s)
John Vinson, Terrence J. Jach, Matthias Mueller, Rainer Unterumsberger, Burkhard Beckhoff
It has been previously shown that two effects cause dramatic changes in the x-ray absorption and emission spectrra from the N K edge of the insulating crystal ammonium nitate. First, vibrational disorder causes major changes in the absorption spectrum

Understanding and Control of Bipolar Doping in Copper Nitride

May 5, 2016
Author(s)
Angela N. Fioretti, Craig P. Schwartz, John Vinson, Dennis Nordlund, David Prendergast, Adele C. Tamboli, Filip Tuomisto, Stephan Lany, Eric S. Toberer, Andriy Zakutayev
Semiconductor materials that can be doped both n-type and p-type are desirable for diode-based applications and transistor technology. Copper nitride (Cu3N) is a metastable semiconductor with a solar-relevant bandgap that has been reported to exhibit

Large-scale core-level Bethe-Salpeter equation calculations

August 31, 2015
Author(s)
Keith Gilmore, John Vinson, Eric L. Shirley, David Prendergast, Chaitanya D. Pemmaraju, Josh J. Kas, John J. Rehr, Fernando D. Vila
We present an efficient implementation of the Bethe-Salpeter equation (BSE) method for obtaining core-level spectra including x-ray absorption (XAS), x-ray emission (XES), and both resonant and non-resonant inelastic x-ray scattering spectra (N/RIXS)

The Multiple Origins of Broadening in Near-edge X-ray Spectra of Nitrogen Compounds

November 10, 2014
Author(s)
John T. Vinson, Terrence J Jach, W. T. Elam, J. D. Denlinger
A comparison of the N Kα emission spectrum of crystalline ammonium nitrate to molecular orbital calculations reveals a unique observation: the peak associated with the σNO recombination is broadened so extensively as to virtually disappear. We have