NMR and EPR

Molecular systems important to biology, environmental remediation and sustainability are studied using a suite of nuclear magnetic resonance (NMR) spectrometers with frequencies ranging from 300 to 850 MHz. A pair of electron paramagnetic resonance (EPR) spectrometers complement the capability.

Description

Interfacial and in situ biology—Innovative NMR instrumentation and techniques for probing properties of macromolecular cellular assemblies and in situ and ex situ metabolic processes, as well as for exploring biological membrane proteins in the solid state. Unique EPR and variable-temperature NMR approaches to explore structure and properties of redox metal centers critical catalysis, environmental chemistry and cell biology.

Environmental chemistry— EMSL offers a unique NMR system for radiological studies. Users can perform magic angle spinning of highly radioactive samples with a novel hermetically sealed 3.2mm NMR probe. These tools allow users to apply NMR techniques to critical areas of radiological research, including the study of radioactive waste processing and storage.

Interfacial and in situ chemistry—Leading-edge solid-state NMR probe technology to analyze and quantify properties of advanced energy materials, fuel cells and real-time catalytic processes. High power pulsed field gradient diffusion capabilities for liquid and solid samples.

 EMSL offers unique and custom NMR and EPR tools, including probes for specialized studies.

  • NMR spectrometers, ranging from 300 MHz to 850 MHz for high-field liquid-state, solid-state and micro-imaging techniques
  • W- and X-band pulsed EPR spectremeter for probing metal centers in biological and materials systems
  • NMR metabolomics capabilities
  • Extreme-temperature probes, both high and low temperatures
  • Virtual NMR tools for remote access to spectrometer systems.

Instruments

Research applications Samples containing paramagnetics Soils (SOM and NOM) Metal oxide materials for catalysis applications Researchers may operate...
Custodian(s): Nancy Washton, Sarah D Burton
Highlighted Research Applications Characterization of natural and soil organic matter (NOM and SOM) CO2 sequestration investigations via high-...
Custodian(s): Sarah D Burton
Highlighted Research Applications EMSL's Bruker 500-MHz WB spectrometer is uniquely tailored for in vivo studies: Microbial biofilms relevant to...
Custodian(s): Ryan Renslow
Type of Instrument:
Nuclear Magnetic Resonance Spectrometer (NMR)
Highlighted Research Applications Dynamics studies via 2H NMR Characterization of quadrupolar nuclei for materials and biological samples In situ...
Highlighted Research Applications Structural biology Protein structure and dynamics Nuclei acid structure and dynamics. Metabolomics Eukaryotic and...
Custodian(s): Nancy Isern

Publications

Zero-valent iron particles are an effective remediation technology for groundwater contaminated with halogenated organic compounds. In particular,...
A series consisting of a tungsten anion, radical and cation, supported by the N-heterocyclic carbene IMes (1,3-bis(2,4,6-trimethylphenyl)imidazol-2-...
An improved synthesis of a 3,4 hydroxypyridinone (HOPO) functionalized mesoporous silica is described. Higher 3,4-HOPO monolayer ligand loadings...
Commonly used in biotechnology applications, filamentous M13 phage are non-lytic viruses that infect E. coli and other bacteria, with the potential...
Homogenous catalysts utilize discrete molecular species which imparts high selectivity and facilitates mechanistic understanding, but encounter...

Science Highlights

Posted: August 14, 2014
Industry uses zeolites as an ion exchange material and solid acid to catalyze a broad range of chemical reactions. Zeolites are also promising...
Posted: June 23, 2014
Congratulations to Pacific Northwest National Laboratory and EMSL researchers on being named highly cited authors for 2012-2013 by the Journal of...
Posted: November 12, 2013
Tiny electrical wires protrude from some bacteria and contribute to rock and dirt formation. Researchers studying the protein that makes up one such...
Posted: May 22, 2013
Bacteria can move electrons at least half a millimeter across a scaffolding made by themselves, of themselves, even under starving conditions. This...
Posted: March 04, 2013
Using EMSL’s electron paramagnetic resonance spectrometer, University of Connecticut and Pacific Northwest National Laboratory scientists measured...

Molecular systems important to biology, environmental remediation and sustainability are studied using a suite of nuclear magnetic resonance (NMR) spectrometers with frequencies ranging from 300 to 850 MHz. A pair of electron paramagnetic resonance (EPR) spectrometers complement the capability.

Quantitatively Probing the Al Distribution in Zeolites.

Abstract: 

The degree of substitution of Si4+ by Al3+ in the oxygen-terminated tetrahedra (Al T-sites) of zeolites determines the concentration of ion-exchange and Brønsted acid sites. As the location of the tetrahedra and the associated subtle variations in bond angles influence the acid strength, quantitative information about Al T-sites in the framework is critical to rationalize catalytic properties and to design new catalysts. A quantitative analysis is reported that uses a combination of extended X-ray absorption fine structure (EXAFS) analysis and 27Al MAS NMR spectroscopy supported by DFT-based molecular dynamics simulations. To discriminate individual Al atoms, sets of ab initio EXAFS spectra for various T-sites are generated from DFT-based molecular dynamics simulations allowing quantitative treatment of the EXAFS single- and multiple-photoelectron scattering processes out to 3-4 atom shells surrounding the Al absorption center. It is observed that identical zeolite types show dramatically different Al-distributions. A preference of Al for T-sites that are part of one or more 4-member rings in the framework over those T-sites that are part of only 5- and 6-member rings in the HBEA150 sample has been determined from a combination of these methods. This work was supported by the U. S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences.

Citation: 
Vjunov A, JL Fulton, T Huthwelker, S Pin, D Mei, GK Schenter, N Govind, DM Camaioni, JZ Hu, and JA Lercher.2014."Quantitatively Probing the Al Distribution in Zeolites."Journal of the American Chemical Society 136(23):8296-8306. doi:10.1021/ja501361v
Authors: 
A Vjunov
JL Fulton
T Huthwelker
S Pin
D Mei
GK Schenter
N Govind
DM Camaioni
JZ Hu
JA Lercher
Instruments: 
Volume: 
136
Issue: 
23
Pages: 
8296-8306
Publication year: 
2014

Molecular Structure and Stability of Dissolved Lithium Polysulfide Species.

Abstract: 

Ability to predict the solubility and stability of lithium polysulfide is vital in realizing longer lasting lithium-sulfur batteries. Herein we report a combined computational and experimental spectroscopic analysis to understand the dissolution mechanism of lithium polysulfide species in an aprotic solvent medium. Multinuclear NMR and sulfur K-edge X-ray absorption (XAS) analysis reveals that the lithium exchange between polysulfide species and solvent molecule constitutes the first step in the dissolution process. Lithium exchange leads to de-lithiated polysulfide ions which subsequently forms highly reactive free radicals through disproportion reaction. The energy required for the disproportion and possible dimer formation reactions of the polysulfide species are analyzed using density functional theory (DFT) calculations. We validate our calculations with variable temperature electron spin resonance (ESR) measurements. Based on these findings, we discuss approaches to optimize the electrolyte in order to control the polysulfide solubility. The energy required for the disproportion and possible dimer formation reactions of the polysulfide species are analyzed using density functional theory (DFT) calculations. We validate our calculations with variable temperature electron spin resonance (ESR) measurements. Based on these findings, we discuss approaches to optimize the electrolyte in order to control the polysulfide solubility.

Citation: 
Vijayakumar M, N Govind, ED Walter, SD Burton, AK Shukla, A Devaraj, J Xiao, J Liu, CM Wang, AM Karim, and S Thevuthasan.2014."Molecular Structure and Stability of Dissolved Lithium Polysulfide Species."Physical Chemistry Chemical Physics. PCCP 16(22):10923-10932. doi:10.1039/c4cp00889H
Authors: 
M Vijayakumar
N Govind
ED Walter
SD Burton
AK Shukla
A Devaraj
J Xiao
J Liu
CM Wang
AM Karim
S Thevuthasan
Instruments: 
Volume: 
16
Issue: 
22
Pages: 
10923-10932
Publication year: 
2014

Mineralization of Basalts in the CO2-H2O-SO2-O2 System.

Abstract: 

Sequestering carbon dioxide (CO2) containing minor amounts of co-contaminants in geologic formations was investigated in the laboratory through the use of high pressure static experiments. Five different basalt samples were immersed in water equilibrated with supercritical CO2 containing 1wt% sulfur dioxide (SO2) and 1wt% oxygen (O2) at reservoir conditions (~100 bar, 90°C) for 49 and 98 days. Gypsum (CaSO4) was a common precipitate, occurred early as elongated blades with striations, and served as substrates for other mineral products. Bimodal pulses of water released during dehydroxylation were key indicators along with X-ray diffraction for verifying the presences of jarosite-alunite group minerals. Well-developed pseudocubic jarosite crystals formed surface coatings, and in some instances mixtures of natrojarosite and natroalunite aggregated into spherically shaped structures measuring 100 μm in diameter. Reaction products were also characterized using infrared spectroscopy, which indicated OH and Fe-O stretching modes. The presences of jarosite-alunite group minerals were found in the lower wavenumber region from 700–400 cm-1. A strong preferential incorporation of Fe(III) into natrojarosite was attributed to the oxidation potential of O2. Evidence of CO2 was detected during thermal decomposition of precipitates, suggesting the onset of mineral carbonation.

Citation: 
Schaef HT, JA Horner, AT Owen, CJ Thompson, JS Loring, and BP McGrail.2014."Mineralization of Basalts in the CO2-H2O-SO2-O2 System."Environmental Science & Technology 48(9):5298-5305. doi:10.1021/es404964j
Authors: 
HT Schaef
JA Horner
AT Owen
CJ Thompson
JS Loring
BP McGrail
Volume: 
48
Issue: 
9
Pages: 
5298-5305
Publication year: 
2014

A Facile Approach Using MgCl2 to Formulate High Performance Mg2+ Electrolytes for Rechargeable Mg Batteries.

Abstract: 

Rechargeable Mg batteries have been regarded as a viable battery technology for grid scale energy storage and transportation applications. However, the limited performance of Mg2+ electrolytes has been a primary technical hurdle to develop high energy density rechargeable Mg batteries. In this study, MgCl2 is demonstrated as a non-nucleophilic and cheap Mg2+ source in combining with Al Lewis acids (AlCl3, AlPh3 and AlEtCl2) to formulate a series of Mg2+ electrolytes characteristic of high oxidation stability (up to 3.4 V vs Mg), sulfur compatibility and electrochemical reversibility (up to 100% coulombic efficiency). Three electrolyte systems (MgCl2-AlCl3, MgCl2-AlPh3, and MgCl2-AlEtCl2) were prepared free of purification and fully characterized by multinuclear NMR (27Al{1H} and 25Mg{1H}) spectroscopies, single crystal X-ray diffraction, and electrochemical analysis. The reaction mechanism of MgCl2 and the Al Lewis acids in THF is discussed to highlight the formation of the electrochemically active [(µ-Cl)3Mg2(THF)6]+ monocation in these electrolytes. We are grateful for the financial support from the Pacific Northwest National Laboratory (PNNL)-Laboratory Directed Research and Development (LDRD) program for developing magnesium battery technology. The XRD and SEM data were collected at the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at PNNL. PNNL is a multiprogram laboratory operated by Battelle Memorial Institute for the Department of Energy under Contract DE-AC05-76RL01830.

Citation: 
Liu TL, Y Shao, G Li, M Gu, JZ Hu, S Xu, Z Nie, X Chen, CM Wang, and J Liu.2014."A Facile Approach Using MgCl2 to Formulate High Performance Mg2+ Electrolytes for Rechargeable Mg Batteries."Journal of Materials Chemistry A 2(10):3430 - 3438. doi:10.1039/c3ta14825d
Authors: 
TL Liu
Y Shao
G Li
M Gu
JZ Hu
S Xu
Z Nie
X Chen
CM Wang
J Liu
Volume: 
Issue: 
Pages: 
Publication year: 
2014

Electrochemical Kinetics and Performance of Layered CompositeCathode Material Li[Li0.2Ni0.2Mn0.6]O2.

Abstract: 

Lithium-rich, manganese-rich (LMR) layered composite cathode material Li[Li0.2Ni0.2Mn0.6]O2 has been successfully prepared by a co-precipitation method and its structure is confirmed by XRD characterization. The material delivers a high discharge capacity of 281 mAh g-1, when charged and discharged at a low current density of 10 mA g-1. However, significant increase of cell polarization and decrease of discharge capacity are observed at voltages below 3.5 V with increasing current densities. Galvanostatic intermittent titration technique (GITT) analysis demonstrates that lithium ion intercalation/de-intercalation reactions in this material are kinetically controlled by Li2MnO3 and its activated MnO2 component. The relationship between the electrochemical kinetics and rate performance as well as cycling stability has been systematically investigated. High discharge capacity of 149 mAh g-1 can be achieved at 10 C charge rate and C/10 discharge rate. The result demonstrates that the Li2MnO3 based material could withstand high charge rate (except initial activation process), which is very promising for practical applications. A lower discharge current density is preferred to overcome the kinetic barrier of lithium ion intercalation into MnO2 component, in order to achieve higher discharge capacity even at high charge rates.

Citation: 
Zheng J, W Shi, M Gu, J Xiao, P Zuo, CM Wang, and J Zhang.2013."Electrochemical Kinetics and Performance of Layered CompositeCathode Material Li[Li0.2Ni0.2Mn0.6]O2."Journal of the Electrochemical Society 160(11):A2212-A2219. doi:10.1149/2.090311jes
Authors: 
J Zheng
W Shi
M Gu
J Xiao
P Zuo
CM Wang
J Zhang
Instruments: 
Volume: 
Issue: 
Pages: 
Publication year: 
2013

Controlled Nucleation and Growth Process of Li2S2/Li2S in Lithium-Sulfur Batteries.

Abstract: 

Lithium-sulfur battery is a promising next-generation energy storage system because of its potentially three to five times higher energy density than that of traditional lithium ion batteries. However, the dissolution and precipitation of soluble polysulfides during cycling initiate a series of key-chain reactions that significantly shorten battery life. Herein, we demonstrate that through a simple but effective strategy, significantly improved cycling performance is achieved for high sulfur loading electrodes through controlling the nucleation and precipitation of polysulfieds on the electrode surface. More than 400 or 760 stable cycling are successfully displayed in the cells with locked discharge capacity of 625 mAh g-1 or 500 mAh g-1, respectively. The nucleation and growth process of dissolved polysulfides has been electrochemically altered to confine the thickness of discharge products passivated on the cathode surface, increasing the utilization rate of sulfur while avoiding severe morphology changes on the electrode. More importantly, the exposure of new lithium metal surface to the S-containing electrolyte is also greatly reduced through this strategy, largely minimizing the anode corrosion caused by polysulfides. This work interlocks the electrode morphologies and its evolution with electrochemical interference to modulate cell performances by using Li-S system as a platform, providing different but critical directions for this community.

Citation: 
Zheng J, M Gu, CM Wang, P Zuo, PK Koech, J Zhang, J Liu, and J Xiao.2013."Controlled Nucleation and Growth Process of Li2S2/Li2S in Lithium-Sulfur Batteries."Journal of the Electrochemical Society 160(11):A1992-A1996. doi:10.1149/2.032311jes
Authors: 
J Zheng
M Gu
CM Wang
P Zuo
PK Koech
J Zhang
J Liu
J Xiao
Instruments: 
Volume: 
Issue: 
Pages: 
Publication year: 
2013

Diffusion in biofilms respiring on electrodes.

Abstract: 

The goal of this study was to measure spatially and temporally resolved effective diffusion coefficients (De) in biofilms respiring on electrodes. Two model electrochemically active biofilms, Geobacter sulfurreducens PCA and Shewanella oneidensis MR-1, were investigated. A novel nuclear magnetic resonance microimaging perfusion probe capable of simultaneous electrochemical and pulsed-field gradient nuclear magnetic resonance (PFG-NMR) techniques was used. PFG-NMR allowed for noninvasive, nondestructive, high spatial resolution in situ De measurements in living biofilms respiring on electrodes. The electrodes were polarized so that they would act as the sole terminal electron acceptor for microbial metabolism. We present our results as both two-dimensional De heat maps and surface-averaged relative effective diffusion coefficient (Drs) depth profiles. We found that (1) Drs decreases with depth in G. sulfurreducens biofilms, following a sigmoid shape; (2) Drs at a given location decreases with G. sulfurreducens biofilm age; (3) average De and Drs profiles in G. sulfurreducens biofilms are lower than those in S. oneidensis biofilms—the G. sulfurreducens biofilms studied here were on average 10 times denser than the S. oneidensis biofilms; and (4) halting the respiration of a G. sulfurreducens biofilm decreases the De values. Density, reflected by De, plays a major role in the extracellular electron transfer strategies of electrochemically active biofilms.

Citation: 
Renslow RS, JT Babauta, PD Majors, and H Beyenal.2013."Diffusion in biofilms respiring on electrodes."Energy and Environmental Science 6(2):595-607. doi:10.1039/C2EE23394K
Authors: 
RS Renslow
JT Babauta
PD Majors
H Beyenal
Volume: 
6
Issue: 
2
Pages: 
595-607
Publication year: 
2013

Catalyst Activity Comparison of Alcohols over Zeolites.

Abstract: 

Alcohol transformation to transportation fuel range hydrocarbon on HZSM-5 (SiO2 / Al2O3 = 30) catalyst was studied at 360oC and 300psig. Product distributions and catalyst life were compared using methanol, ethanol, 1-propanol or 1-butanol as a feed. The catalyst life for 1-propanol and 1-butanol was more than double compared to that for methanol and ethanol. For all the alcohols studied, the product distributions (classified to paraffin, olefin, napthene, aromatic and naphthalene compounds) varied with time on stream (TOS). At 24 hours TOS, liquid product from 1-propanol and 1-butanol transformation primarily contains higher olefin compounds. The alcohol transformation process to higher hydrocarbon involves a complex set of reaction pathways such as dehydration, oligomerization, dehydrocyclization, and hydrogenation. Compared to ethylene generated from methanol and ethanol, oligomerization of propylene and butylene has a lower activation energy and can readily take place on weaker acidic sites. On the other hand, dehydrocyclization of propylene and butylene to form the cyclic compounds requires the sits with stronger acid strength. Combination of the above mentioned reasons are the primary reasons for olefin rich product generated in the later stage of the time on stream and for the extended catalyst life time for 1 propanol and 1 butanol compared to methanol and ethanol conversion over HZSM-5.

Citation: 
Ramasamy KK, and Y Wang.2013."Catalyst Activity Comparison of Alcohols over Zeolites."Journal of Energy Chemistry 22(1):65-71.
Authors: 
KK Ramasamy
Y Wang
Instruments: 
Volume: 
22
Issue: 
1
Pages: 
65-71
Publication year: 
2013

Mineralization of Basalts in the CO2-H2O-H2S System.

Abstract: 

Basalt samples representing five different formations were immersed in water equilibrated with supercritical carbon dioxide containing 1% hydrogen sulfide (H2S) at reservoir conditions (100 bar, 90°C) for up to 3.5 years. Surface coatings in the form of pyrite and metal cation substituted carbonates were identified as reaction products associated with all five basalts. In some cases, high pressure tests contained excess H2S, which produced the most corroded basalts and largest amount of secondary products. In comparison, tests containing limited amounts of H2S appeared least reacted with significantly less concentrations of reaction products. In all cases, pyrite appeared to precede carbonation, and in some instances, was observed in the absence of carbonation such as in cracks, fractures, and within the porous glassy mesostasis. Armoring reactions from pyrite surface coatings observed in earlier shorter duration tests were found to be temporary with carbonate mineralization observed with all the basalts tested in these long duration experiments. Geochemical simulations conducted with the geochemical code EQ3/6 accurately predicted early pyrite precipitation followed by formation of carbonates. Reactivity with H2S was correlated with measured Fe(II)/Fe(III) ratios in the basalts with more facile pyrite formation occurring with basalts containing more Fe(III) phases. These experimental and modeling results confirm potential for long term sequestration of acid gas mixtures in continental flood basalt formations.

Citation: 
Schaef HT, BP McGrail, AT Owen, and BW Arey.2013."Mineralization of Basalts in the CO2-H2O-H2S System."International Journal of Greenhouse Gas Control 16:187-196. doi:10.1016/j.ijggc.2013.03.020
Authors: 
HT Schaef
BP McGrail
AT Owen
BW Arey
Instruments: 
Volume: 
Issue: 
Pages: 
Publication year: 
2013

Molecular Active Sites in Heterogeneous Ir-La/C Catalyzed Carbonylation of Methanol to Acetates.

Abstract: 

Homogenous catalysts utilize discrete molecular species which imparts high selectivity and facilitates mechanistic understanding, but encounter separation and stability problems. Since they are more stable and easily separated, heterogeneous catalysts are more widely used in industry, but normally contain a multiplicity of sites leading to reduced selectivity and difficult mechanistic interpretations. Attaining molecular (single site) behavior similar to homogenous catalysts on heterogeneous surfaces has been an enduring goal. Here we show that when Ir and La halides are deposited on carbon, exposure to CO spontaneously generates a discrete molecular heterobimetallic species containing an Ir-La covalent bond, likely IrLa(CO)2Cl4. The generation of these discrete species on the surface leads to a highly active and selective heterogeneous catalyst for the carbonylation of methanol to produce acetic acid, in which enhanced activity may be mechanistically rationalized based on the chemistry of lanthanide-transition metal complexes and earlier studies on the Ir catalyzed methanol carbonylations. Acknowledgements: This research was supported by Eastman Chemical Company and by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle under contract number DE-AC05-76RL01830. The electron microscopy work carried out at the Oak Ridge National Laboratory's High Temperature Materials Laboratory was sponsored by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program.

Citation: 
Kwak JH, RA Dagle, GC Tustin, JR Zoeller, LF Allard, and Y Wang.2014."Molecular Active Sites in Heterogeneous Ir-La/C Catalyzed Carbonylation of Methanol to Acetates."Journal of Physical Chemistry Letters 5(3):566-572. doi:10.1021/jz402728e
Authors: 
JH Kwak
RA Dagle
GC Tustin
JR Zoeller
LF Allard
Y Wang
Instruments: 
Volume: 
5
Issue: 
3
Pages: 
566-572
Publication year: 
2014

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