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Kaseman DC, Batrice RJ, Williams RF. Detection of natural abundance 13C J-couplings at Earth's magnetic field for spin system differentiation of small organic molecules. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 342:107272. [PMID: 35917767 DOI: 10.1016/j.jmr.2022.107272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/14/2022] [Accepted: 07/21/2022] [Indexed: 06/15/2023]
Abstract
Nuclear magnetic resonance (NMR) spectroscopy routinely characterizes the unique spin systems of molecules using a combination of chemical shift and J-coupling interactions for the 1H and 13C nuclei. However, at Earth's magnetic field, chemical shifts are unresolvable and the ability to characterize structure relies solely on the J-couplings. Fortuitously, the J-couplings at Earth's field provides the same spin system information as high field, but only requires detection of the 1H nucleus. We report the first identification of the multiple natural abundance 1H-13C spin systems on organic molecules detected at Earth's magnetic field. The results clearly demonstrate the feasibility of Earth's field NMR to characterize small organic molecules without costly enrichment strategies.
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Affiliation(s)
- Derrick C Kaseman
- Bioenergy and Biome Sciences Group, Los Alamos National Laboratory, Los Alamos, NM 87545, United States; Nuclear Magnetic Resonance Facility, University of California Davis, Davis, CA 95616, United States.
| | - Rami J Batrice
- Chemical Diagnostics and Engineering Group, Los Alamos National Laboratory, Los Alamos, NM 87545, United States
| | - Robert F Williams
- Bioenergy and Biome Sciences Group, Los Alamos National Laboratory, Los Alamos, NM 87545, United States
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2
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Kaseman DC, Malone MW, Tondreau A, Espy MA, Williams RF. Quantitation of Nuclear Magnetic Resonance Spectra at Earth's Magnetic Field. Anal Chem 2021; 93:15349-15357. [PMID: 34747610 DOI: 10.1021/acs.analchem.1c02910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The inherently quantitative nature of nuclear magnetic resonance (NMR) spectroscopy is one of the most attractive aspects of this analytical technique. Quantitative NMR analyses have typically been limited to high-field (>1 T) applications. The aspects for quantitation at low magnetic fields (<1 mT) have not been thoroughly investigated and are shown to be impacted by the complex signatures that arise at these fields from strong heteronuclear J-couplings. This study investigates quantitation at Earth's magnetic field (∼50 μT) for a variety of samples in strongly, weakly, and uncoupled spin systems. To achieve accurate results in this regime, the instrumentation, experimental acquisition, processing, and theoretical aspects must be considered and reconciled. Of particular note is the constant field nuclear receptivity equation, which has been re-derived in this study to account for strong coupling and quality factor effects. The results demonstrate that the quantitation of homonuclear molecular groups, determination of heteronuclear pseudoempirical formulas, and mixture analysis are all feasible at Earth's magnetic field in a greatly simplified experimental system.
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Affiliation(s)
- Derrick C Kaseman
- Biome and Bioenergy Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Michael W Malone
- Quantum Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Aaron Tondreau
- Inorganic, Isotope, and Actinide Chemistry Group, Los Alamos, New Mexico 87545, United States
| | - Michelle A Espy
- Non-Destructive Testing and Evaluation Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Robert F Williams
- Biome and Bioenergy Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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3
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Bengs C, Dagys L, Levitt MH. Robust transformation of singlet order into heteronuclear magnetisation over an extended coupling range. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 321:106850. [PMID: 33190080 DOI: 10.1016/j.jmr.2020.106850] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/06/2020] [Accepted: 10/09/2020] [Indexed: 06/11/2023]
Abstract
Several important NMR procedures involve the conversion of nuclear singlet order into heteronuclear magnetisation, including some experiments involving long-lived spin states and parahydrogen-induced hyperpolarisation. However most existing sequences suffer from a limited range of validity or a lack of robustness against experimental imperfections. We present a new radio-frequency scheme for the transformation of the singlet order of a chemically-equivalent homonuclear spin pair into the magnetisation of a heteronuclear coupling partner. The proposed radio-frequency (RF) scheme is called gS2hM (generalized singlet-to-heteronuclear magnetisation) and has good compensation for common experimental errors such as RF and static field inhomogeneities. The sequence retains its robustness for homonuclear spin pairs in the intermediate coupling regime, characterised by the in-pair coupling being of the same order of magnitude as the difference between the out-of-pair couplings. This is a substantial improvement to the validity range of existing sequences. Analytical solutions for the pulse sequence parameters are provided. Experimental results are shown for two test cases.
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Affiliation(s)
- Christian Bengs
- School of Chemistry, Southampton University, University Road, SO17 1BJ, UK.
| | - Laurynas Dagys
- School of Chemistry, Southampton University, University Road, SO17 1BJ, UK.
| | - Malcolm H Levitt
- School of Chemistry, Southampton University, University Road, SO17 1BJ, UK.
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4
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Chemical Analysis of Fluorobenzenes via Multinuclear Detection in the Strong Heteronuclear J-Coupling Regime. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10113836] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chemical analysis via nuclear magnetic resonance (NMR) spectroscopy using permanent magnets, rather than superconducting magnets, is a rapidly developing field. Performing the NMR measurement in the strong heteronuclear J-coupling regime has shown considerable promise for the chemical analysis of small molecules. Typically, the condition for the strong heteronuclear J-coupling regime is satisfied at µT magnetic field strengths and enables high resolution J-coupled spectra (JCS) to be acquired. However, the JCS response to systematic chemical structural changes has largely not been investigated. In this report, we investigate the JCS of C6H6−xFx (x = 0, 1, 2, …, 6) fluorobenzene compounds via simultaneous excitation and detection of 19F and 1H at 51.5 µT. The results demonstrate that JCS are quantitative, and the common NMR observables, including Larmor frequency, heteronuclear and homonuclear J-couplings, relative signs of the J-coupling, chemical shift, and relaxation, are all measurable and are differentiable between molecules at low magnetic fields. The results, corroborated by ab initio calculations, provide new insights into the impact of chemical structure and their corresponding spin systems on JCS. In several instances, the JCS provided more chemical information than traditional high field NMR, demonstrating that JCS can be used for robust chemical analysis.
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5
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Kaseman DC, Magnelind PE, Widgeon Paisner S, Yoder JL, Alvarez M, Urbaitis AV, Janicke MT, Nath P, Espy MA, Williams RF. Design and implementation of a J-coupled spectrometer for multidimensional structure and relaxation detection at low magnetic fields. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:054103. [PMID: 32486714 DOI: 10.1063/1.5130391] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 04/09/2020] [Indexed: 06/11/2023]
Abstract
In recent years, it has been realized that low and ultra-low field (mT-nT magnetic field range) nuclear magnetic resonance spectroscopy can be used for molecular structural analysis. However, spectra are often hindered by lengthy acquisition times or require large sample volumes and high concentrations. Here, we report a low field (50 μT) instrument that employs a linear actuator to shuttle samples between a 1 T prepolarization field and a solenoid detector in a laboratory setting. The current experimental setup is benchmarked using water and 13C-methanol with a single scan detection limit of 2 × 1020 spins (3 µl, 55M H2O) and detection limit of 2.9 × 1019 (200 µl, 617 mM 13C-methanol) spins with signal averaging. The system has a dynamic range of >3 orders of magnitude. Investigations of room-temperature relaxation dynamics of 13C-methanol show that sample dilution can be used in lieu of sample heating to acquire spectra with linewidths comparable to high-temperature spectra. These results indicate that the T1 and T2 mechanisms are governed by both the proton exchange rate and the dissolved oxygen in the sample. Finally, a 2D correlation spectroscopy experiment is reported, performed in the strong coupling regime that resolves the multiple resonances associated with the heteronuclear J-coupling. The spectrum was collected using 10 times less sample and in less than half the time from previous reports in the strong coupling limit.
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Affiliation(s)
- Derrick C Kaseman
- Bioenergy and Biome Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Per E Magnelind
- Quantum Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Scarlett Widgeon Paisner
- Materials Science in Radiation and Dynamics Extremes Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Jacob L Yoder
- Bioenergy and Biome Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Marc Alvarez
- Bioenergy and Biome Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Algis V Urbaitis
- Quantum Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Michael T Janicke
- Inorganic, Isotope and Actinide Chemistry Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Pulak Nath
- Quantum Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Michelle A Espy
- Non-destructive Testing and Evaluation Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Robert F Williams
- Bioenergy and Biome Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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6
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Zhu Y, Gao Y, Rodocker S, Savukov I, Hilty C. Multinuclear Detection of Nuclear Spin Optical Rotation at Low Field. J Phys Chem Lett 2018; 9:3323-3327. [PMID: 29787279 DOI: 10.1021/acs.jpclett.8b01053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We describe the multinuclear detection of nuclear spin optical rotation (NSOR), an effect dependent on the hyperfine interaction between nuclear spins and electrons. Signals of 1H and 19F are discriminated by frequency in a single spectrum acquired at sub-millitesla field. The simultaneously acquired optical signal along with the nuclear magnetic resonance signal allows the calculation of the relative magnitude of the NSOR constants corresponding to different nuclei within the sample molecules. This is illustrated by a larger NSOR signal measured at the 19F frequency despite a smaller corresponding spin concentration. Second, it is shown that heteronuclear J-coupling is observable in the NSOR signal, which can be used to retrieve chemical information. Multinuclear frequency and J resolution can localize optical signals in the molecule. Properties of electronic states at multiple sites in a molecule may therefore ultimately be determined by frequency-resolved NSOR spectroscopy at low field.
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Affiliation(s)
- Yue Zhu
- Chemistry Department , Texas A&M University , 3255 TAMU , College Station , Texas 77843 , United States
| | - Yuheng Gao
- Chemistry Department , Texas A&M University , 3255 TAMU , College Station , Texas 77843 , United States
| | - Shane Rodocker
- Chemistry Department , Texas A&M University , 3255 TAMU , College Station , Texas 77843 , United States
| | - Igor Savukov
- New Mexico Consortium , 100 Entrada Drive , Los Alamos , New Mexico 87544 , United States
| | - Christian Hilty
- Chemistry Department , Texas A&M University , 3255 TAMU , College Station , Texas 77843 , United States
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7
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Buckenmaier K, Rudolph M, Back C, Misztal T, Bommerich U, Fehling P, Koelle D, Kleiner R, Mayer HA, Scheffler K, Bernarding J, Plaumann M. SQUID-based detection of ultra-low-field multinuclear NMR of substances hyperpolarized using signal amplification by reversible exchange. Sci Rep 2017; 7:13431. [PMID: 29044168 PMCID: PMC5647402 DOI: 10.1038/s41598-017-13757-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 09/26/2017] [Indexed: 11/15/2022] Open
Abstract
Ultra-low-field (ULF) nuclear magnetic resonance (NMR) is a promising spectroscopy method allowing for, e.g., the simultaneous detection of multiple nuclei. To overcome the low signal-to-noise ratio that usually hampers a wider application, we present here an alternative approach to ULF NMR, which makes use of the hyperpolarizing technique signal amplification by reversible exchange (SABRE). In contrast to standard parahydrogen hyperpolarization, SABRE can continuously hyperpolarize 1 H as well as other MR-active nuclei. For simultaneous measurements of 1 H and 19 F under SABRE conditions a superconducting quantum interference device (SQUID)-based NMR detection unit was adapted. We successfully hyperpolarized fluorinated pyridine derivatives with an up to 2000-fold signal enhancement in 19 F. The detected signals may be explained by two alternative reaction mechanisms. SABRE combined with simultaneous SQUID-based broadband multinuclear detection may enable the quantitative analysis of multinuclear processes.
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Affiliation(s)
- K Buckenmaier
- High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Spemannstr. 41, 72076, Tübingen, Germany.
| | - M Rudolph
- High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Spemannstr. 41, 72076, Tübingen, Germany.,Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, University of Tübingen, Tübingen, Germany
| | - C Back
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, University of Tübingen, Tübingen, Germany
| | - T Misztal
- Institute of Inorganic Chemistry, University of Tübingen, Tübingen, Germany
| | - U Bommerich
- Department for Biometrics and Medical Informatics, Otto-von-Guericke University, Magdeburg, Germany
| | - P Fehling
- High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Spemannstr. 41, 72076, Tübingen, Germany
| | - D Koelle
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, University of Tübingen, Tübingen, Germany
| | - R Kleiner
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, University of Tübingen, Tübingen, Germany
| | - H A Mayer
- Institute of Inorganic Chemistry, University of Tübingen, Tübingen, Germany
| | - K Scheffler
- High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Spemannstr. 41, 72076, Tübingen, Germany
| | - J Bernarding
- Department for Biometrics and Medical Informatics, Otto-von-Guericke University, Magdeburg, Germany
| | - M Plaumann
- Department for Biometrics and Medical Informatics, Otto-von-Guericke University, Magdeburg, Germany
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8
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Zhu Y, Chen CH, Wilson Z, Savukov I, Hilty C. Milli-tesla NMR and spectrophotometry of liquids hyperpolarized by dissolution dynamic nuclear polarization. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 270:71-76. [PMID: 27423094 DOI: 10.1016/j.jmr.2016.06.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 06/18/2016] [Accepted: 06/21/2016] [Indexed: 06/06/2023]
Abstract
Hyperpolarization methods offer a unique means of improving low signal strength obtained in low-field NMR. Here, simultaneous measurements of NMR at a field of 0.7mT and laser optical absorption from samples hyperpolarized by dissolution dynamic nuclear polarization (D-DNP) are reported. The NMR measurement field closely corresponds to a typical field encountered during sample injection in a D-DNP experiment. The optical spectroscopy allows determination of the concentration of the free radical required for DNP. Correlation of radical concentration to NMR measurement of spin polarization and spin-lattice relaxation time allows determination of relaxivity and can be used for optimization of the D-DNP process. Further, the observation of the nuclear Overhauser effect originating from hyperpolarized spins is demonstrated. Signals from (1)H and (19)F in a mixture of trifluoroethanol and water are detected in a single spectrum, while different atoms of the same type are distinguished by J-coupling patterns. The resulting signal changes of individual peaks are indicative of molecular contact, suggesting a new application area of hyperpolarized low-field NMR for the determination of intermolecular interactions.
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Affiliation(s)
- Yue Zhu
- Chemistry Department, Texas A&M University, 3255 TAMU, College Station, TX 77843, USA
| | - Chia-Hsiu Chen
- Chemistry Department, Texas A&M University, 3255 TAMU, College Station, TX 77843, USA
| | - Zechariah Wilson
- Chemistry Department, Texas A&M University, 3255 TAMU, College Station, TX 77843, USA
| | - Igor Savukov
- New Mexico Consortium, 100 Entrada Drive, Los Alamos, NM 87544, USA
| | - Christian Hilty
- Chemistry Department, Texas A&M University, 3255 TAMU, College Station, TX 77843, USA.
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9
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Bevilacqua G, Biancalana V, Baranga ABA, Dancheva Y, Rossi C. Microtesla NMR J-coupling spectroscopy with an unshielded atomic magnetometer. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 263:65-70. [PMID: 26773528 DOI: 10.1016/j.jmr.2015.12.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 12/25/2015] [Accepted: 12/29/2015] [Indexed: 06/05/2023]
Abstract
We present experimental data and theoretical interpretation of NMR spectra of remotely magnetized samples, detected in an unshielded environment by means of a differential atomic magnetometer. The measurements are performed in an ultra-low-field at an intermediate regime, where the J-coupling and the Zeeman energies have comparable values and produce rather complex line sets, which are satisfactorily interpreted.
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10
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Shim JH, Lee SJ, Hwang SM, Yu KK, Kim K. Two-dimensional NMR spectroscopy of (13)C methanol at less than 5 μT. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 246:4-8. [PMID: 25063950 DOI: 10.1016/j.jmr.2014.06.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 06/19/2014] [Accepted: 06/20/2014] [Indexed: 06/03/2023]
Abstract
Two-dimensional (2D) spectroscopy is one of the most significant applications of nuclear magnetic resonance (NMR). Here, we demonstrate that the 2D NMR can be performed even at a low magnetic field of less than 5μT, which is ten times less than the Earth's magnetic field. The pulses used in the experiment were composed of circularly polarized fields for coherent as well as wideband excitations. Since the excitation band covers the entire spectral range, the simplest two-pulse sequence delivered the full 2D spectrum. At 5μT, methanol with (13)C enriched up to 99% belongs to a strongly coupled regime, and thus its 2D spectrum exhibits complicated spectral correlations, which can be exploited as a fingerprint in chemical analysis. In addition, we show that, with compressive sensing, the acquisition of the 2D spectrum can be accelerated to take only 45% of the overall duration.
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Affiliation(s)
- Jeong Hyun Shim
- (a)Center for Biosignals, Korea Research Institute of Standards and Science, Daejeon 350-340, Republic of Korea.
| | - Seong-Joo Lee
- (a)Center for Biosignals, Korea Research Institute of Standards and Science, Daejeon 350-340, Republic of Korea
| | - Seong-min Hwang
- (a)Center for Biosignals, Korea Research Institute of Standards and Science, Daejeon 350-340, Republic of Korea
| | - Kwon-Kyu Yu
- (a)Center for Biosignals, Korea Research Institute of Standards and Science, Daejeon 350-340, Republic of Korea
| | - Kiwoong Kim
- (a)Center for Biosignals, Korea Research Institute of Standards and Science, Daejeon 350-340, Republic of Korea; (b)Department of Medical Physics, University of Science and Technology, Daejeon 305-333, Republic of Korea
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11
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Theis T, Blanchard JW, Butler MC, Ledbetter MP, Budker D, Pines A. Chemical analysis using J-coupling multiplets in zero-field NMR. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.06.042] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12
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Butler MC, Ledbetter MP, Theis T, Blanchard JW, Budker D, Pines A. Multiplets at zero magnetic field: The geometry of zero-field NMR. J Chem Phys 2013; 138:184202. [DOI: 10.1063/1.4803144] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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13
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Koptyug IV. MRI of mass transport in porous media: drying and sorption processes. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 65:1-65. [PMID: 22781314 DOI: 10.1016/j.pnmrs.2011.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 12/05/2011] [Indexed: 06/01/2023]
Affiliation(s)
- Igor V Koptyug
- International Tomography Center, SB RAS, 3A Institutskaya Str., Novosibirsk 630090, Russian Federation.
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14
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Fridjonsson EO, Flux LS, Johns ML. Determination of mean droplet sizes of water-in-oil emulsions using an Earth's field NMR instrument. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 221:97-102. [PMID: 22750255 DOI: 10.1016/j.jmr.2012.05.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 05/17/2012] [Accepted: 05/21/2012] [Indexed: 06/01/2023]
Abstract
The use of the Earth's magnetic field (EF) to conduct nuclear magnetic resonance (NMR) experiments has a long history with a growing list of applications (e.g. ground water detection, diffusion measurements of Antarctic sea ice). In this paper we explore whether EFNMR can be used to accurately and practically measure the mean droplet size (<a>) of water-in-oil emulsions (paraffin and crude oil). We use both pulsed field gradient (PFG) measurements of restricted self-diffusion and T₂ relaxometry, as appropriate. T₂ relaxometry allows the extension of droplet sizing ability below the limits set by the available magnetic field gradient strength of the EFNMR apparatus. A commercially available bench-top NMR spectrometer is used to verify the results obtained using the EFNMR instrument, with good agreement within experimental error, seen between the two instruments. These results open the potential for further investigation of the application of EFNMR for emulsion droplet sizing.
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Affiliation(s)
- Einar O Fridjonsson
- School of Mechanical and Chemical Engineering, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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15
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Theis T, Ledbetter MP, Kervern G, Blanchard JW, Ganssle PJ, Butler MC, Shin HD, Budker D, Pines A. Zero-Field NMR Enhanced by Parahydrogen in Reversible Exchange. J Am Chem Soc 2012; 134:3987-90. [DOI: 10.1021/ja2112405] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Thomas Theis
- Department
of Chemistry, University of California at Berkeley, Berkeley, California 94720-3220, United States
| | - Micah P. Ledbetter
- Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300,
United States
| | - Gwendal Kervern
- Department
of Chemistry, University of California at Berkeley, Berkeley, California 94720-3220, United States
| | - John W. Blanchard
- Department
of Chemistry, University of California at Berkeley, Berkeley, California 94720-3220, United States
| | - Paul J. Ganssle
- Department
of Chemistry, University of California at Berkeley, Berkeley, California 94720-3220, United States
| | - Mark C. Butler
- Department
of Chemistry, University of California at Berkeley, Berkeley, California 94720-3220, United States
| | - Hyun D. Shin
- Department
of Chemistry, University of California at Berkeley, Berkeley, California 94720-3220, United States
| | - Dmitry Budker
- Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300,
United States
| | - Alexander Pines
- Department
of Chemistry, University of California at Berkeley, Berkeley, California 94720-3220, United States
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16
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17
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Homonuclear decoupled proton NMR spectra in modest to severe inhomogeneous fields via distant dipolar interactions. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.04.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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NMR spectroscopy in the milli-Tesla regime: Measurement of 1H chemical-shift differences below the line width. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2009.11.066] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Halse ME, Callaghan PT, Feland BC, Wasylishen RE. Quantitative analysis of Earth's field NMR spectra of strongly-coupled heteronuclear systems. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 200:88-94. [PMID: 19596600 DOI: 10.1016/j.jmr.2009.06.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 06/10/2009] [Indexed: 05/28/2023]
Abstract
In the Earth's magnetic field, it is possible to observe spin systems consisting of unlike spins that exhibit strongly coupled second-order NMR spectra. Such spectra result when the J-coupling between two unlike spins is of the same order of magnitude as the difference in their Larmor precession frequencies. Although the analysis of second-order spectra involving only spin-(1/2) nuclei has been discussed since the early days of NMR spectroscopy, NMR spectra involving spin-(1/2) nuclei and quadrupolar (I>(1/2)) nuclei have rarely been treated. Two examples are presented here, the tetrahydroborate anion, BH4-, and the ammonium cation, NH4+. For the tetrahydroborate anion, (1)J((11)B,(1)H)=80.9Hz, and in an Earth's field of 53.3microT, nu((1)H)=2269Hz and nu((11)B)=728Hz. The (1)H NMR spectra exhibit features that both first- and second-order perturbation theory are unable to reproduce. On the other hand, second-order perturbation theory adequately describes (1)H NMR spectra of the ammonium anion, (14)NH4+, where (1)J((14)N,(1)H)=52.75Hz when nu((1)H)=2269Hz and nu((14)N)=164Hz. Contrary to an early report, we find that the (1)H NMR spectra are independent of the sign of (1)J((14)N,(1)H). Exact analysis of two-spin systems consisting of quadrupolar nuclei and spin-(1/2) nuclei are also discussed.
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Affiliation(s)
- Meghan E Halse
- MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, Post Office Box 600, Wellington 6012, New Zealand
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Pileio G, Carravetta M, Levitt MH. Extremely low-frequency spectroscopy in low-field nuclear magnetic resonance. PHYSICAL REVIEW LETTERS 2009; 103:083002. [PMID: 19792724 DOI: 10.1103/physrevlett.103.083002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Indexed: 05/28/2023]
Abstract
We demonstrate a new phenomenon in nuclear magnetic resonance spectroscopy, in which nuclear spin transitions are induced by radio frequency irradiation at extremely low frequencies (of the order of a few Hz). Slow Rabi oscillations are observed between spin states of different exchange symmetry. These "forbidden" transitions are rendered weakly allowed by differential electronic shielding effects on the radio frequency field. We generate coherence between the singlet and triplet states of 15N-labeled nitrous oxide in solution, and estimate the scalar coupling between the two 15N nuclei with a precision of a few mHz.
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Affiliation(s)
- Giuseppe Pileio
- School of Chemistry, Southampton University, SO17 1BJ, United Kingdom
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