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Our research examines the structures and dynamics of materials in which organization of complex compositions over small length scales occurs: high surface area layered, exfoliated, or mesoporous metal oxides and inorganic/organic nanocomposites. Elucidation of these complex structures and motions is possible with the use of advanced scattering, both neutron and x-ray, and solid state NMR techniques. The combination of scattering and NMR allows for the study of dynamics over a large timescale (picoseconds to seconds) and of structures looking at the local environment through to long range order.
1) Local Structure and Properties in High Surface Metal Oxides via NMRThe local coordination and symmetry of a surface species affects the properties of that site. An understanding of what factors control the distortions necessary to alter the surface properties is needed to intelligently tailor the reactivity of mesoporous or nanoscopic oxides and exfoliated nanosheets. These materials are of interest due to their potential to serve as catalysts, proton conductors, and building blocks for novel nanostructured materials. In the case of materials that are not amenable to traditional characterization via diffraction, these surface sites are difficult to characterize. However, spectroscopic methods that are not dependent on long-range order and are element selective have the potential to illuminate the nature of these species. To develop this correlation, we employ solid-state NMR methodologies such as multiple quantum magic angle spinning (MQMAS) and quadrupolar phase adjusted sideband suppression (QPASS), to examine the NMR active isotopes of early transition metals in these oxides. Information based on the electric field gradient sensed by a quadrupolar nucleus and the chemical shift anisotropy, both created by the arrangement and bonding of oxygen atoms surrounding the metal atom, are used to determine the local structure.
2) Nanocomposite Materials using Metal Oxide Mesoporous HostsUse of mesoporous oxides as confinement hosts is desirable due to their ordered nature, high surface area, and tunable well-defined pore sizes. These factors make mesoporous oxides useful hosts to study the effects of encapsulation of organic or inorganic species using NMR and quasielastic neutron scattering (QENS). The oxide host can affect the motion of the polymer through the interaction between the walls and polymer units. Confinement can also alter the phase that is produced from the synthesis of inorganic oxides in the cavities. Our research will focus on the incorporation of polymer electrolyte materials and lithium conducting inorganic oxides.
3) Polymer-blend based Lithium Polymer ElectrolytesSolid polymer electrolytes have been pursued as a replacement for the liquid solvents used in current battery systems due to safety and performance issues. The polymer bland work centers on combining a high molecular weight PMMA lithium ionomer block co-polymer with a low molecular weight species to create a semi-rigid film that contains a mobile phase for lithium conduction. The goal is to introduce the dynamics of a liquid phase while retaining the mechanical strength of a heavier polymer. To determine the efficacy of these materials as a transport medium, the environment and mobility of the lithium cation in the channels are characterized through solid-state NMR methods. In particular, transport studies are conducted using the pulsed field gradient NMR facilities available at Clark University, which are well suited to measure the slow diffusion of the lithium atoms.
Degrees
- Ph.D. in Chemistry, University of California, Santa Barbara, 1999
- M.A. in Chemistry, University of California, Santa Barbara, 1995
- B.S. in Chemistry, University of Chicago, 1993
Affiliated Department(s)
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Scholarly and Creative Works
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Structural properties of optically clear bacterial cellulose produced by Komagataeibacter hansenii using arabitol
Published in Biomater. Adv.
Spring
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2023
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Vol. 148
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PIETA Based Pathway Selection of Non-frequency Dispersed Echoes in WURST-CPMG
61st Rocky Mountain Conference on Magnetic Resonance
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Copper Mountain, CO
July
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2022
Sponsored by Colorado Section – American Chemical Society & Society for Applied Spectroscopy
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Synthesis of nickel-doped Dion-Jacobson perovskites through multistep molten salt, salt flux, and ion exchange methods
ACS Spring 2021/ACS National Meeting
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Virtual
April
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2021
Sponsored by American Chemical Society
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Strategies for Extending Zeolite Stability in Supercritical Water Using Thermally Stable Coatings
Published in ACS Catalysis
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2020
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Effects of Composition and Processing on Bismuth-containing Layered Perovskites
New England Energy Research Forum
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Worcester, MA
June
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2019
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Size and Morphology Control of Copper (I) Oxide Hexapod Nanostructures
New England Energy Research Forum
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Worcester, MA
June
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2019
Sponsored by WPI Energy Research Group
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Sulfonated hybrid mesoporous silica-polymer particles as solid-acid catalysts for cellulose hydrolysis and as solid electrolytes for lithium ion batteries.
257th ACS National Meeting & Exposition
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Orlando, FL
March
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2019
Sponsored by American Chemical Society
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ZSM-5 decrystallization and dealumination in hot liquid water.
Published in Phys. Chem. Chem. Phys.
2019///
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2019
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Vol. 21
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Issue #32
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93Nb NMR Structural Analysis of Acid-Exchanged Layered Bismuth Niobate Perovskites with Varying Band Gaps
59th Rocky Mountain Conference on Magnetic Resonance
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Snowbird, UT
July
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2018
Sponsored by Colorado Section – American Chemical Society & the Society for Applied Spectroscopy
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Ion dynamics in solid polymer blend electrolytes via inversion of the laplace transform.
Ion dynamics in solid polymer blend electrolytes via inversion of the laplace transform.
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2018///
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2018
Sponsored by American Chemical Society
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Visible absorbance variation in Dion-Jacobson perovskites upon acid exchange.
Visible absorbance variation in Dion-Jacobson perovskites upon acid exchange.
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2018///
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2018
Sponsored by American Chemical Society
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Rapid synthetic strategy for Cu2O hexapod synthesis.
Rapid synthetic strategy for Cu2O hexapod synthesis.
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2018///
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2018
Sponsored by American Chemical Society
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Structure and band gap analysis for new Dion-Jacobson perovskite RbBiKNb3O10.
Structure and band gap analysis for new Dion-Jacobson perovskite RbBiKNb3O10.
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2018///
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2018
Sponsored by American Chemical Society
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Rapid Microwave-Assisted Grafting of Layered Perovskites with n-Alcohols.
Published in Inorg. Chem.
2015///
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2015
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Vol. 54
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Issue #9
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Exfoliation of layered perovskites through microwave assisted grafting with n-alcohols.
Exfoliation of layered perovskites through microwave assisted grafting with n-alcohols.2015///
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2015
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Diblock and triblock lithium conducting polymers from strongly incompatible PEGMA and PAAMPSA segments, effect of interdomain surface area on morphology and ionic transport.
Diblock and triblock lithium conducting polymers from strongly incompatible PEGMA and PAAMPSA segments, effect of interdomain surface area on morphology and ionic transport.2015///
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2015
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Poly(ethylenimine)-Based Polymer Blends as Single-Ion Lithium Conductors.
Published in Macromolecules (Washington, DC, U. S.)
2014///
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2014
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Vol. 47
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Issue #10
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Active membrane having uniform physico-chemically functionalized ion channels.
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2013
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Unique battery with an active membrane separator having uniform physicochemically functionalized ion channels and a method making the same.
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2012
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Unique battery with a multi-functional, physicochemically active membrane separator/electrolyte-electrode monolith and a method of making the same.
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2012
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Structural characterization of layered perovskite niobates using projector augmented wave (PAW) method of density functional theory (DFT).
Structural characterization of layered perovskite niobates using projector augmented wave (PAW) method of density functional theory (DFT).2010///
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2010
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Design of triazole bearing sol-gel membranes as water free proton exchange membranes for hydrogen fuel cells, effect of crosslink density, and heterocycle content on membrane performance.
Design of triazole bearing sol-gel membranes as water free proton exchange membranes for hydrogen fuel cells, effect of crosslink density, and heterocycle content on membrane performance.2010///
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2010
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93Nb solid state NMR study of Dion-Jacobson type layered niobates XLaNb2O7 (X=Cs, Rb, K, H).
93Nb solid state NMR study of Dion-Jacobson type layered niobates XLaNb2O7 (X=Cs, Rb, K, H).2010///
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2010
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Conductivity and component diffusion study of a solid lithium polymer electrolyte based on the polymer blend of PEG and PMMA doped with LiTFSI.
Conductivity and component diffusion study of a solid lithium polymer electrolyte based on the polymer blend of PEG and PMMA doped with LiTFSI.2010///
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2010
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Structural investigation of a layered Dion-Jacobson perovskite, RbSr2Nb3O10 and its acidic form, HSr2Nb3O10 using density functional theory.
Structural investigation of a layered Dion-Jacobson perovskite, RbSr2Nb3O10 and its acidic form, HSr2Nb3O10 using density functional theory.2009///
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2009
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Incomplete double frequency sweeps to select small quadrupolar coupling static powder patterns.
Published in Solid State Nucl. Magn. Reson.
2009///
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2009
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Vol. 36
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Issue #2
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An Investigation of Distortions of the Dion-Jacobson Phase RbSr2Nb3O10 and Its Acid-Exchanged Form with 93Nb Solid State NMR and DFT Calculations.
Published in J. Phys. Chem. C
2009///
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2009
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Vol. 113
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Issue #40
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Solid-state NMR strategies for characterizing high surface area niobates.
Published in J. Mol. Catal. A: Chem.
2008///
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2008
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Vol. 281
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Issue #1-2
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Structural Investigation of KCa2Nb3O10 and Its Acidic Form HCa2Nb3O10- Using Density Functional Theory for Calculations of NMR Parameters.
Structural Investigation of KCa2Nb3O10 and Its Acidic Form HCa2Nb3O10- Using Density Functional Theory for Calculations of NMR Parameters.2008///
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2008
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Exploring the Local Structure of Layered Niobate Materials by 93Nb Solid State NMR.
Exploring the Local Structure of Layered Niobate Materials by 93Nb Solid State NMR.2008///
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2008
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Component Diffusion In LiTFSI Doped Polymer Blend of PEGDME and PMMA Measured by Multinuclear PFG NMR.
Component Diffusion In LiTFSI Doped Polymer Blend of PEGDME and PMMA Measured by Multinuclear PFG NMR.2008///
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2008
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NMR Studies of Proton Exchange Induced Structural Changes In Layered and Mesoporous Niobates.
NMR Studies of Proton Exchange Induced Structural Changes In Layered and Mesoporous Niobates.2008///
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2008
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93Nb solid state NMR of high surface area niobium oxides.
Published in Mater. Res. Soc. Symp. Proc.
2007///
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2007
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Vol. 984E
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Issue #Magnetic Resonance in Material Science
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Analysis of porosity in porous silicon using hyperpolarized 129Xe two-dimensional exchange experiments.
Published in Solid State Nucl. Magn. Reson.
2006///
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2006
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Vol. 29
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Issue #1-3
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Site-selective QPASS for the isolation of large quadrupolar coupling environments.
Published in J. Magn. Reson.
2006///
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2006
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Vol. 179
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Issue #1
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A unified approach to the dynamics of a polymer melt.
Published in J. Phys.: Condens. Matter
2006///
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2006
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Vol. 18
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Issue #36
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Substrate and Field Dependence of the SPINOE Transfer to Surface 13C from Hyperpolarized 129Xe.
Published in J. Phys. Chem. B
2005///
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2005
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Vol. 109
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Issue #10
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Inelastic neutron scattering as a probe of dynamics under confinement. The case of a PEO polymer melt.
Published in Ann. Chim. (Cachan, Fr.)
2005///
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2005
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Vol. 30
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Issue #4
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Molecular dynamics of glucose in solution: A quasielastic neutron scattering study.
Published in J. Chem. Phys.
2004///
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2004
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Vol. 120
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Issue #8
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Dynamics of Water Molecules in Glucose Solutions.
Published in J. Phys. Chem. B
2004///
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2004
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Vol. 108
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Issue #16
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Characterization of polymer nanocomposites used in rechargeable systems.
Characterization of polymer nanocomposites used in rechargeable systems.2003///
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2003
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Characterization of polymer nanocomposites used in rechargeable systems.
Published in Prepr. Symp. - Am. Chem. Soc., Div. Fuel Chem.
2003///
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2003
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Vol. 48
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Issue #1
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Characterization of polymer clay nanocomposite electrolyte motions via combined NMR and neutron scattering studies.
Published in Mater. Res. Soc. Symp. Proc.
2003///
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2003
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Vol. 756
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Issue #Solid State Ionics--2002
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Frozen-Solution Conformational Analysis by REDOR Spectroscopy.
Published in J. Am. Chem. Soc.
2003///
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2003
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Vol. 125
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Issue #49
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Investigating hyperpolarized 129Xe and CPMAS for spin polarization transfer to surface nuclei: a model study.
Published in J. Magn. Reson.
2002///
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2002
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Vol. 159
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Issue #2
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Potassium Cation Effects on Site Preferences in the Mixed Cation Zeolite Li,Na-Chabazite.
Published in Chem. Mater.
2001///
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2001
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Vol. 13
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Issue #2
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Variable Temperature Study of the Cross-Relaxation Dynamics in the Hyperpolarized Xenon-Induced Enhancement of Surface Nuclei.
Published in J. Phys. Chem. B
2001///
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2001
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Vol. 105
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Issue #7
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Hyperpolarized xenon-mediated cross-polarization to material surfaces observed at room temperature and above.
Published in J. Am. Chem. Soc.
2001///
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2001
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Vol. 123
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Issue #12
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Site Preferences in the Mixed Cation Zeolite, Li,Na-Chabazite: A Combined Solid-State NMR and Neutron Diffraction Study.
Published in J. Am. Chem. Soc.
2000///
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2000
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Vol. 122
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Issue #8
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Site preferences in a mixed alkali cation zeolite, Chabazite, studied through MQMAS NMR and neutron diffraction.
Site preferences in a mixed alkali cation zeolite, Chabazite, studied through MQMAS NMR and neutron diffraction.1999///
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1999
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Cation locations and dislocations in zeolites.
1999///
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1999
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A neutron diffraction and infrared spectroscopy study of the acid form of the aluminosilicate zeolite, chabazite (H-SSZ-13).
Published in Catal. Lett.
1998///
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1998
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Vol. 49
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Issue #3,4
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Some factors influencing metal-insulator transitions.
Published in Z. Anorg. Allg. Chem.
1996///
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1996
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Vol. 622
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Issue #10
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Awards & Grants
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An integrated study of ion dynamics and population distributions to understand the molecular underpinnings of charge transport through self-assembled solid polymer electrolytes
National Science Foundation
Jul. 1, 2018 - Jun. 30, 2022
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