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Nir-Arad O, Shlomi DH, Israelstam A, Amit T, Manukovsky N, Fialkov AB, Kaminker I. The CW-EPR Capabilities of a Dual DNP/EPR Spectrometer Operating at 14 and 7 T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 360:107635. [PMID: 38401475 DOI: 10.1016/j.jmr.2024.107635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 12/24/2023] [Accepted: 02/07/2024] [Indexed: 02/26/2024]
Abstract
High-field electron paramagnetic resonance (EPR) measurements are indispensable for a better understanding of dynamic nuclear polarization (DNP), which relies on polarization transfer between electron and nuclear spins. DNP experiments are typically performed at high > 7 T magnetic fields and low ≤ 100 K temperatures, while EPR instrumentation capable of EPR measurements under these conditions is scarce. In this paper, we describe the CW EPR capabilities of a dual DNP/EPR spectrometer that is designed to carry out EPR experiments under "DNP conditions" at 14 and 7 T. In the first part, we present the design of this instrument, highlighting the choices made to allow for both DNP and EPR operations. The spectrometer uses a sweepable cryogen-free magnet with NMR-grade homogeneity, a closed-cycle cooling system, a quasi-optical induction mode bridge, and a superheterodyne receiver system. The probe design is optimized for low heat load and fast sample exchange under cryogenic conditions. The spectrometer can operate in frequency and field sweep modes, including wide field sweeps using the main coil of the magnet. In the second part, we present EPR spectra acquired over a wide range of samples and operating conditions, illustrating the CW EPR capabilities of the instrument.
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Affiliation(s)
- Orit Nir-Arad
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - David H Shlomi
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Amit Israelstam
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Tomer Amit
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Nurit Manukovsky
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Alexander B Fialkov
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ilia Kaminker
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
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2
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Tagami K, Thicklin R, Jain S, Equbal A, Li M, Zens T, Siaw A, Han S. Design of a cryogen-free high field dual EPR and DNP probe. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 347:107351. [PMID: 36599253 DOI: 10.1016/j.jmr.2022.107351] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 11/29/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
We present the design and construction of a cryogen free, dual electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) probe for novel dynamic nuclear polarization (DNP) experiments and concurrent "in situ" analysis of DNP mechanisms. We focus on the probe design that meets the balance between EPR, NMR, and low temperature performance, while maintaining a high degree of versatility: allowing multi-nuclear NMR detection as well as broadband DNP/EPR excitation/detection. To accomplish high NMR/EPR performance, we implement a novel inductively coupled double resonance NMR circuit (1H-13C) in a solid state probe operating at cryogenic temperatures. The components of the circuit were custom built to provide maximum NMR performance, and the physical layout of this circuit was numerically optimized via magnetic field simulations to allow maximum microwave transmission to the sample for optimal EPR performance. Furthermore this probe is based around a cryogen free gas exchange cryostat and has been designed to allow unlimited experiment times down to 8.5 Kelvin with minimal cost. The affordability of EPR/DNP experiment is an extremely important aspect for broader impact with magnetic resonance measurements. The purpose of this article is to provide as complete information as we have available for others with interest in building a dual DNP/EPR instrument based around a cryogen-free cryostat.
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Affiliation(s)
- Kan Tagami
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Raymond Thicklin
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Sheetal Jain
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Asif Equbal
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Miranda Li
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Toby Zens
- JEOL USA, Inc., 11 Dearborn Road, Peabody, MA 01960, United States
| | - Anthony Siaw
- JEOL USA, Inc., 11 Dearborn Road, Peabody, MA 01960, United States
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States; Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106, United States.
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3
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Tang X, Suddarth S, Kantesaria S, Garwood M. A frequency-swept, longitudinal detection EPR system for measuring short electron spin relaxation times at ultra-low fields. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 342:107279. [PMID: 35952409 DOI: 10.1016/j.jmr.2022.107279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 06/27/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Abstract
A frequency-swept longitudinal detection (LOD) EPR system is described for ultra-low field spectroscopy and relaxometry. With the capability of performing simultaneous transmit and receive with -80 dB isolation, this LOD-EPR can capture signals with decay constants in the nanosecond range and in theory even sub-nanosecond range, at fields close to the earth's magnetic field. The theoretical principles underlying this LOD-EPR are based on a fictitious field that accounts for the Z-axis magnetization polarized by a radiofrequency field alone. The electron spin relaxation time is obtained directly from a previously derived equation that describes the relationship between the relaxation time and the spectral peak position. Herein, the first frequency-swept LOD-EPR system is described in detail, along with experimental measurements of the short relaxation time (∼30 ns) of the free radical, 2,2-diphenyl-1-picrylhydrazyl, at zero to low field.
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Affiliation(s)
- Xueyan Tang
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, 2021 6(th) Street SE, Minneapolis, MN 55455, USA
| | - Steven Suddarth
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, 2021 6(th) Street SE, Minneapolis, MN 55455, USA
| | - Saurin Kantesaria
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, 2021 6(th) Street SE, Minneapolis, MN 55455, USA
| | - Michael Garwood
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, 2021 6(th) Street SE, Minneapolis, MN 55455, USA.
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4
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Lê TP, Hyacinthe JN, Capozzi A. How to improve the efficiency of a traditional dissolution dynamic nuclear polarization (dDNP) apparatus: Design and performance of a fluid path compatible dDNP/LOD-ESR probe. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 338:107197. [PMID: 35344922 DOI: 10.1016/j.jmr.2022.107197] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 03/12/2022] [Accepted: 03/14/2022] [Indexed: 06/14/2023]
Abstract
Dissolution Dynamic Nuclear Polarization (dDNP) was invented almost twenty years ago. Ever since, hardware advancement has observed 2 trends: the quest for DNP at higher field and, more recently, the development of cryogen free polarizers. Despite the DNP community is slowly migrating towards "dry" systems, many "wet" polarizers are still in use. Traditional DNP polarizers can use up to 100 L of liquid helium per week, but are less sensitive to air contamination and have higher cooling power. These two characteristics make them very versatile when it comes to new methods development. In this study we retrofitted a 5 T/1.15 K "wet" DNP polarizer with the aim of improving cryogenic and DNP performance. We designed, built, and tested a new DNP insert that is compatible with the fluid path (FP) technology and a LOgitudinal Detected Electron Spin Resonance (LOD-ESR) probe to investigate radical properties at real DNP conditions. The new hardware increased the maximum achievable polarization and the polarization rate constant of a [1-13C]pyruvic acid-trityl sample by a factor 1.5. Moreover, the increased liquid He holding time together with the possibility to constantly keep the sample space at low pressure upon sample loading and dissolution allowed us to save about 20 L of liquid He per week.
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Affiliation(s)
- Thanh Phong Lê
- Geneva School of Health Sciences, HES-SO University of Applied Sciences and Arts Western Switzerland, Avenue de Champel 47, 1206 Geneva, Switzerland; LIFMET, Institute of Physics, École polytechnique fédérale de Lausanne (EPFL), Station 6, 1015 Lausanne, Switzerland
| | - Jean-Noël Hyacinthe
- Geneva School of Health Sciences, HES-SO University of Applied Sciences and Arts Western Switzerland, Avenue de Champel 47, 1206 Geneva, Switzerland; Image Guided Interventions Laboratory, Department of Radiology and Medical Informatics, University of Geneva, Rue Gabrielle-Perret-Gentil 4, 1211 Geneva, Switzerland
| | - Andrea Capozzi
- LIFMET, Institute of Physics, École polytechnique fédérale de Lausanne (EPFL), Station 6, 1015 Lausanne, Switzerland; HYPERMAG, Department of Health Technology, Technical University of Denmark, Building 349, 2800 Kgs Lyngby, Denmark.
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5
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Elliott SJ, Stern Q, Ceillier M, El Daraï T, Cousin SF, Cala O, Jannin S. Practical dissolution dynamic nuclear polarization. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2021; 126-127:59-100. [PMID: 34852925 DOI: 10.1016/j.pnmrs.2021.04.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 04/09/2021] [Indexed: 06/13/2023]
Abstract
This review article intends to provide insightful advice for dissolution-dynamic nuclear polarization in the form of a practical handbook. The goal is to aid research groups to effectively perform such experiments in their own laboratories. Previous review articles on this subject have covered a large number of useful topics including instrumentation, experimentation, theory, etc. The topics to be addressed here will include tips for sample preparation and for checking sample health; a checklist to correctly diagnose system faults and perform general maintenance; the necessary mechanical requirements regarding sample dissolution; and aids for accurate, fast and reliable polarization quantification. Herein, the challenges and limitations of each stage of a typical dissolution-dynamic nuclear polarization experiment are presented, with the focus being on how to quickly and simply overcome some of the limitations often encountered in the laboratory.
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Affiliation(s)
- Stuart J Elliott
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs - UMR 5082 Université de Lyon, CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France
| | - Quentin Stern
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs - UMR 5082 Université de Lyon, CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France
| | - Morgan Ceillier
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs - UMR 5082 Université de Lyon, CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France
| | - Théo El Daraï
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs - UMR 5082 Université de Lyon, CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France
| | - Samuel F Cousin
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs - UMR 5082 Université de Lyon, CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France
| | - Olivier Cala
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs - UMR 5082 Université de Lyon, CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France
| | - Sami Jannin
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs - UMR 5082 Université de Lyon, CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France.
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6
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Gennaro A, Karabanov A, Potapov A, Köckenberger W. Heteronuclear DNP of 1H and 19F nuclei using BDPA as a polarizing agent. Phys Chem Chem Phys 2020; 22:7803-7816. [DOI: 10.1039/d0cp00892c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The study reveals heteronuclear-thermal mixing – a novel mechanism of dynamic nuclear polarization in a system with 1H and 19F nuclei.
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Affiliation(s)
- Antonio Gennaro
- School of Physics and Astronomy
- University of Nottingham
- Nottingham
- UK
| | | | - Alexey Potapov
- School of Physics and Astronomy
- University of Nottingham
- Nottingham
- UK
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7
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Jähnig F, Himmler A, Kwiatkowski G, Däpp A, Hunkeler A, Kozerke S, Ernst M. A spin-thermodynamic approach to characterize spin dynamics in TEMPO-based samples for dissolution DNP at 7 T field. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 303:91-104. [PMID: 31030064 DOI: 10.1016/j.jmr.2019.04.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 04/12/2019] [Accepted: 04/19/2019] [Indexed: 06/09/2023]
Abstract
The spin dynamics of dissolution DNP samples consisting of 4.5 M [13C]urea in a mixture of (1/1)Vol glycerol/water using 4-Oxo-TEMPO as a radical was investigated. We analyzed the DNP dynamics as function of radical concentration at 7 T and 3.4 T static magnetic field as well as function of deuteration of the solvent matrix at the high field. The spin dynamics could be reproduced in all cases, at least qualitatively, by a thermodynamic model based on spin temperatures of the nuclear Zeeman baths and an electron non-Zeeman (dipolar) bath. We find, however, that at high field (7 T) and low radical concentrations (25 mM) the nuclear spins do not reach the same spin temperature indicating a weak coupling of the two baths. At higher radical concentrations, as well as for all radical concentrations at low field (3.4 T), the two nuclear Zeeman baths reach the same spin temperature within experimental errors. Additionally, the spin system was prepared with different initial conditions. For these cases, the thermodynamic model was able to predict the time evolution of the system well. While the DNP profiles do not give clear indications to a specific polarization transfer mechanism, at high field (7 T) increased coupling is seen. The EPR line shapes cannot clarify this in absence of ELDOR type experiments, nevertheless DNP profiles and dynamics under frequency-modulated microwave irradiation illustrate the expected increase in coupling between electrons with increasing radical concentration.
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Affiliation(s)
- Fabian Jähnig
- Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Aaron Himmler
- Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Grzegorz Kwiatkowski
- Institute for Biomedical Engineering, University and ETH Zürich, Gloriastrasse 35, 8092 Zürich, Switzerland
| | - Alexander Däpp
- Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Andreas Hunkeler
- Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zürich, Gloriastrasse 35, 8092 Zürich, Switzerland
| | - Matthias Ernst
- Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland.
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8
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Filibian M, Elisei E, Colombo Serra S, Rosso A, Tedoldi F, Cesàro A, Carretta P. Nuclear magnetic resonance studies of DNP-ready trehalose obtained by solid state mechanochemical amorphization. Phys Chem Chem Phys 2016; 18:16912-20. [PMID: 27282123 DOI: 10.1039/c6cp00914j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
(1)H nuclear spin-lattice relaxation and Dynamic Nuclear Polarization (DNP) have been studied in amorphous samples of trehalose sugar doped with TEMPO radicals by means of mechanical milling, in the 1.6-4.2 K temperature range. The radical concentration was varied between 0.34 and 0.81%. The highest polarization of 15% at 1.6 K, observed in the sample with concentration 0.50%, is of the same order of magnitude of that reported in standard frozen solutions with TEMPO. The temperature and concentration dependence of the spin-lattice relaxation rate 1/T1, dominated by the coupling with the electron spins, were found to follow power laws with an exponent close to 3 in all samples. The observed proportionality between 1/T1 and the polarization rate 1/Tpol, with a coefficient related to the electron polarization, is consistent with the presence of Thermal Mixing (TM) and a good contact between the nuclear and the electron spins. At high electron concentration additional relaxation channels causing a decrease in the nuclear polarization must be considered. These results provide further support for a more extensive use of amorphous DNP-ready samples, obtained by means of comilling, in dissolution DNP experiments and possibly for in vivo metabolic imaging.
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Affiliation(s)
- M Filibian
- Department of Physics, University of Pavia-CNISM, Via Bassi 6, 27100 Pavia, Italy.
| | - E Elisei
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via Giorgieri 1, 34127 Trieste, Italy and UMET, Unité Matériaux et Transformations, CNRS, Univ. Lille, F-59000 Lille, France
| | - S Colombo Serra
- Bracco Research Center, Bracco Imaging S.p.A., Via, Ribes 5, 10010 Colleretto Giacosa (TO), Italy
| | - A Rosso
- Laboratoire de Physique Théorique et Modèles Statistiques (UMR CNRS 8626), Université Paris-Sud, Bât. 100, 15 rue Georges Clémenceau, 91405 Orsay Cedex, France
| | - F Tedoldi
- Bracco Research Center, Bracco Imaging S.p.A., Via, Ribes 5, 10010 Colleretto Giacosa (TO), Italy
| | - A Cesàro
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via Giorgieri 1, 34127 Trieste, Italy and Elettra Sincrotrone Trieste, Area Science Park, I-34149 Trieste, Italy
| | - P Carretta
- Department of Physics, University of Pavia-CNISM, Via Bassi 6, 27100 Pavia, Italy.
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9
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Siaw TA, Leavesley A, Lund A, Kaminker I, Han S. A versatile and modular quasi optics-based 200GHz dual dynamic nuclear polarization and electron paramagnetic resonance instrument. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 264:131-153. [PMID: 26920839 PMCID: PMC4770585 DOI: 10.1016/j.jmr.2015.12.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 12/19/2015] [Accepted: 12/21/2015] [Indexed: 05/12/2023]
Abstract
Solid-state dynamic nuclear polarization (DNP) at higher magnetic fields (>3T) and cryogenic temperatures (∼ 2-90K) has gained enormous interest and seen major technological advances as an NMR signal enhancing technique. Still, the current state of the art DNP operation is not at a state at which sample and freezing conditions can be rationally chosen and the DNP performance predicted a priori, but relies on purely empirical approaches. An important step towards rational optimization of DNP conditions is to have access to DNP instrumental capabilities to diagnose DNP performance and elucidate DNP mechanisms. The desired diagnoses include the measurement of the "DNP power curve", i.e. the microwave (MW) power dependence of DNP enhancement, the "DNP spectrum", i.e. the MW frequency dependence of DNP enhancement, the electron paramagnetic resonance (EPR) spectrum, and the saturation and spectral diffusion properties of the EPR spectrum upon prolonged MW irradiation typical of continuous wave (CW) DNP, as well as various electron and nuclear spin relaxation parameters. Even basic measurements of these DNP parameters require versatile instrumentation at high magnetic fields not commercially available to date. In this article, we describe the detailed design of such a DNP instrument, powered by a solid-state MW source that is tunable between 193 and 201 GHz and outputs up to 140 mW of MW power. The quality and pathway of the transmitted and reflected MWs is controlled by a quasi-optics (QO) bridge and a corrugated waveguide, where the latter couples the MW from an open-space QO bridge to the sample located inside the superconducting magnet and vice versa. Crucially, the versatility of the solid-state MW source enables the automated acquisition of frequency swept DNP spectra, DNP power curves, the diagnosis of MW power and transmission, and frequency swept continuous wave (CW) and pulsed EPR experiments. The flexibility of the DNP instrument centered around the QO MW bridge will provide an efficient means to collect DNP data that is crucial for understanding the relationship between experimental and sample conditions, and the DNP performance. The modularity of this instrumental platform is suitable for future upgrades and extensions to include new experimental capabilities to meet contemporary DNP needs, including the simultaneous operation of two or more MW sources, time domain DNP, electron double resonance measurements, pulsed EPR operation, or simply the implementation of higher power MW amplifiers.
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Affiliation(s)
- Ting Ann Siaw
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, United States
| | - Alisa Leavesley
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, United States
| | - Alicia Lund
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, United States
| | - Ilia Kaminker
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, United States
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, United States.
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10
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Karabanov A, Kwiatkowski G, Perotto CU, Wiśniewski D, McMaster J, Lesanovsky I, Köckenberger W. Dynamic nuclear polarisation by thermal mixing: quantum theory and macroscopic simulations. Phys Chem Chem Phys 2016; 18:30093-30104. [DOI: 10.1039/c6cp04345c] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A quantum theory of thermal mixing dynamic nuclear polarisation in solids is developed displaying a good agreement with experiments.
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Affiliation(s)
| | | | | | | | | | - Igor Lesanovsky
- School of Physics and Astronomy
- University of Nottingham
- Nottingham
- UK
- Centre for the Mathematics and Theoretical Physics of Quantum Non-equilibrium Systems
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11
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Guy ML, Zhu L, Ramanathan C. Design and characterization of a W-band system for modulated DNP experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 261:11-8. [PMID: 26524649 PMCID: PMC4971581 DOI: 10.1016/j.jmr.2015.09.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 09/29/2015] [Accepted: 09/30/2015] [Indexed: 05/05/2023]
Abstract
Magnetic-field and microwave-frequency modulated DNP experiments have been shown to yield improved enhancements over conventional DNP techniques, and even to shorten polarization build-up times. The resulting increase in signal-to-noise ratios can lead to significantly shorter acquisition times in signal-limited multi-dimensional NMR experiments and pave the way to the study of even smaller sample volumes. In this paper we describe the design and performance of a broadband system for microwave frequency- and amplitude-modulated DNP that has been engineered to minimize both microwave and thermal losses during operation at liquid helium temperatures. The system incorporates a flexible source that can generate arbitrary waveforms at 94GHz with a bandwidth greater than 1GHz, as well as a probe that efficiently transmits the millimeter waves from room temperature outside the magnet to a cryogenic environment inside the magnet. Using a thin-walled brass tube as an overmoded waveguide to transmit a hybrid HE11 mode, it is possible to limit the losses to 1dB across a 2GHz bandwidth. The loss is dominated by the presence of a quartz window used to isolate the waveguide pipe. This performance is comparable to systems with corrugated waveguide or quasi-optical components. The overall excitation bandwidth of the probe is seen to be primarily determined by the final antenna or resonator used to excite the sample and its coupling to the NMR RF coil. Understanding the instrumental limitations imposed on any modulation scheme is key to understanding the observed DNP results and potentially identifying the underlying mechanisms. We demonstrate the utility of our design with a set of triangular frequency-modulated DNP experiments.
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Affiliation(s)
- Mallory L Guy
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755, USA
| | - Lihuang Zhu
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755, USA
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12
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Roy SS, Dumez JN, Stevanato G, Meier B, Hill-Cousins JT, Brown RCD, Pileio G, Levitt MH. Enhancement of quantum rotor NMR signals by frequency-selective pulses. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 250:25-28. [PMID: 25482571 DOI: 10.1016/j.jmr.2014.11.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 11/08/2014] [Accepted: 11/09/2014] [Indexed: 06/04/2023]
Abstract
Quantum-rotor-induced polarisation (QRIP) enhancement is exhibited by substances which contain freely rotating methyl groups in the solid state, provided that the methyl groups contain a (13)C nucleus. Strong signal enhancements are observed in solution NMR when the material is first equilibrated at cryogenic temperatures, then rapidly dissolved with a warm solvent and transferred into an NMR magnet. QRIP leads to strongly-enhanced (13)C NMR signals, but relatively weak enhancements of the (1)H signals. We show that the (1)H signals suffer from a partial cancellation of degenerate contributions, which may be corrected by applying a frequency-selective π pulse to the inner peaks of the (13)C multiplet prior to (1)H observation.
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Affiliation(s)
- Soumya Singha Roy
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, United Kingdom
| | - Jean-Nicolas Dumez
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, United Kingdom; Institut de Chimie des Substances Naturelles, CNRS UPR2301, Avenue de la Terrasse, 91190 Gif-sur-Yvette, France
| | - Gabriele Stevanato
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, United Kingdom
| | - Benno Meier
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, United Kingdom
| | - Joseph T Hill-Cousins
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, United Kingdom
| | - Richard C D Brown
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, United Kingdom
| | - Giuseppe Pileio
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, United Kingdom
| | - Malcolm H Levitt
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, United Kingdom.
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Perez Linde AJ, Bornet A, Milani J, Vuichoud B, Melzi R, Jannin S, Bodenhausen G. Cross polarization from (1)H to quadrupolar (6)Li nuclei for dissolution DNP. Phys Chem Chem Phys 2014; 16:24813-7. [PMID: 25319311 DOI: 10.1039/c4cp03592e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cross polarization from protons to quadrupolar (6)Li nuclei is combined with dynamic nuclear polarization of protons at 1.2 K and 6.7 T using TEMPOL as a polarizing agent followed by rapid dissolution. Compared to direct (6)Li DNP without cross-polarization, a higher nuclear spin polarization P((6)Li) can be obtained in a shorter time. A double resonance (1)H-(6)Li probe was designed that is equipped for Longitudinally Detected Electron Spin Resonance.
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Affiliation(s)
- Angel J Perez Linde
- Institut des Sciences et Ingénierie Chimiques (ISIC), École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
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15
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Meier B, Dumez JN, Stevanato G, Hill-Cousins JT, Roy SS, Håkansson P, Mamone S, Brown RCD, Pileio G, Levitt MH. Long-lived nuclear spin states in methyl groups and quantum-rotor-induced polarization. J Am Chem Soc 2013; 135:18746-9. [PMID: 24252212 DOI: 10.1021/ja410432f] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Substances containing rapidly rotating methyl groups may exhibit long-lived states (LLSs) in solution, with relaxation times substantially longer than the conventional spin-lattice relaxation time T1. The states become long-lived through rapid internal rotation of the CH3 group, which imposes an approximate symmetry on the fluctuating nuclear spin interactions. In the case of very low CH3 rotational barriers, a hyperpolarized LLS is populated by thermal equilibration at liquid helium temperature. Following dissolution, cross-relaxation of the hyperpolarized LLS, induced by heteronuclear dipolar couplings, generates strongly enhanced antiphase NMR signals. This mechanism explains the NMR signal enhancements observed for (13)C-γ-picoline (Icker, M.; Berger, S. J. Magn. Reson. 2012, 219, 1-3).
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Affiliation(s)
- Benno Meier
- School of Chemistry, University of Southampton , SO17 1BJ Southampton, U.K
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Potapov A, Yau WM, Tycko R. Dynamic nuclear polarization-enhanced 13C NMR spectroscopy of static biological solids. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 231:5-14. [PMID: 23562665 PMCID: PMC3660528 DOI: 10.1016/j.jmr.2013.02.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/12/2013] [Accepted: 02/14/2013] [Indexed: 05/21/2023]
Abstract
We explore the possibility of using dynamic nuclear polarization (DNP) to enhance signals in structural studies of biological solids by solid state NMR without sample spinning. Specifically, we use 2D (13)C-(13)C exchange spectroscopy to probe the peptide backbone torsion angles (φ, ψ) in a series of selectively (13)C-labeled 40-residue β-amyloid (Aβ(1-40)) samples, in both fibrillar and non-fibrillar states. Experiments are carried out at 9.39 T and 8 K, using a static double-resonance NMR probe and low-power microwave irradiation at 264 GHz. In frozen solutions of Aβ(1-40) fibrils doped with DOTOPA-TEMPO, we observe DNP signal enhancement factors of 16-21. We show that the orientation- and frequency-dependent spin polarization exchange between sequential backbone carbonyl (13)C labels can be simulated accurately using a simple expression for the exchange rate, after experimentally determined homogeneous (13)C lineshapes are incorporated in the simulations. The experimental 2D (13)C-(13)C exchange spectra place constraints on the φ and ψ angles between the two carbonyl labels. Although the data are not sufficient to determine φ and ψ uniquely, the data do provide non-trivial constraints that could be included in structure calculations. With DNP at low temperatures, 2D (13)C-(13)C exchange spectra can be obtained from a 3.5 mg sample of Aβ(1-40) fibrils in 4 h or less, despite the broad (13)C chemical shift anisotropy line shapes that are observed in static samples.
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Affiliation(s)
- Alexey Potapov
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA.
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Smith AA, Corzilius B, Bryant JA, DeRocher R, Woskov PP, Temkin RJ, Griffin RG. A 140 GHz pulsed EPR/212 MHz NMR spectrometer for DNP studies. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 223:170-9. [PMID: 22975246 PMCID: PMC3459153 DOI: 10.1016/j.jmr.2012.07.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 06/26/2012] [Accepted: 07/09/2012] [Indexed: 05/05/2023]
Abstract
We described a versatile spectrometer designed for the study of dynamic nuclear polarization (DNP) at low temperatures and high fields. The instrument functions both as an NMR spectrometer operating at 212 MHz ((1)H frequency) with DNP capabilities, and as a pulsed-EPR operating at 140 GHz. A coiled TE(011) resonator acts as both an NMR coil and microwave resonator, and a double balanced ((1)H, (13)C) radio frequency circuit greatly stabilizes the NMR performance. A new 140 GHz microwave bridge has also been developed, which utilizes a four-phase network and ELDOR channel at 8.75 GHz, that is then multiplied and mixed to obtain 140 GHz microwave pulses with an output power of 120 mW. Nutation frequencies obtained are as follows: 6 MHz on S=1/2 electron spins, 100 kHz on (1)H, and 50 kHz on (13)C. We demonstrate basic EPR, ELDOR, ENDOR, and DNP experiments here. Our solid effect DNP results demonstrate an enhancement of 144 and sensitivity gain of 310 using OX063 trityl at 80 K and an enhancement of 157 and maximum sensitivity gain of 234 using Gd-DOTA at 20 K, which is significantly better performance than previously reported at high fields (≥3 T).
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Affiliation(s)
- Albert A. Smith
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Björn Corzilius
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jeffrey A. Bryant
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Ronald DeRocher
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Paul P. Woskov
- Plasma Science and Fusion Research Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Richard J. Temkin
- Plasma Science and Fusion Research Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Robert G. Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Correspondence should be addressed:
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Potapov A, Thurber KR, Yau WM, Tycko R. Dynamic nuclear polarization-enhanced ¹H-¹³C double resonance NMR in static samples below 20 K. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 221:32-40. [PMID: 22743540 PMCID: PMC3727229 DOI: 10.1016/j.jmr.2012.05.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 05/07/2012] [Accepted: 05/09/2012] [Indexed: 05/21/2023]
Abstract
We demonstrate the feasibility of one-dimensional and two-dimensional ¹H-¹³C double resonance NMR experiments with dynamic nuclear polarization (DNP) at 9.4 T and temperatures below 20 K, including both ¹H-¹³C cross-polarization and ¹H decoupling, and discuss the effects of polarizing agent type, polarizing agent concentration, temperature, and solvent deuteration. We describe a two-channel low-temperature DNP/NMR probe, capable of carrying the radio-frequency power load required for ¹H-¹³C cross-polarization and high-power proton decoupling. Experiments at 8 K and 16 K reveal a significant T₂ relaxation of ¹³C, induced by electron spin flips. Carr-Purcell experiments and numerical simulations of Carr-Purcell dephasing curves allow us to determine the effective correlation time of electron flips under our experimental conditions. The dependence of the DNP signal enhancement on electron spin concentration shows a maximum near 80 mM. Although no significant difference in the absolute DNP enhancements for triradical (DOTOPA-TEMPO) and biradical (TOTAPOL) dopants was found, the triradical produced greater DNP build-up rates, which are advantageous for DNP experiments. Additionally the feasibility of structural measurements on ¹³C-labeled biomolecules was demonstrated with a two-dimensional ¹³C-¹³C exchange spectrum of selectively ¹³C-labeled β-amyloid fibrils.
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Affiliation(s)
- Alexey Potapov
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Health, Bethesda, MD 20892-0520, USA.
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Batel M, Krajewski M, Weiss K, With O, Däpp A, Hunkeler A, Gimersky M, Pruessmann KP, Boesiger P, Meier BH, Kozerke S, Ernst M. A multi-sample 94 GHz dissolution dynamic-nuclear-polarization system. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 214:166-174. [PMID: 22142831 DOI: 10.1016/j.jmr.2011.11.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 11/04/2011] [Accepted: 11/05/2011] [Indexed: 05/31/2023]
Abstract
We describe the design and initial performance results of a multi-sample dissolution dynamic-nuclear-polarization (DNP) polarizer based on a Helium-temperature NMR cryostat for use in a wide-bore NMR magnet with a room-temperature bore. The system is designed to accommodate up to six samples in a revolver-style sample changer that allows changing samples at liquid-Helium temperature and at pressures ranging from ambient pressure down to 1 mbar. The multi-sample setup is motivated by the desire to do repetitive in vivo measurements and to characterize the DNP process by investigating samples of different chemical composition. The system can be loaded with up to six samples simultaneously to reduce sample loading and unloading. Therefore, series of experiments can be carried out faster and more reliably. The DNP probe contains an oversized microwave cavity and includes EPR and NMR capabilities for monitoring the DNP process. In the solid state, DNP enhancements corresponding to ∼45% polarization for [1-(13)C]pyruvic acid with a trityl radical have been measured. In the initial liquid-state acquisition experiments described here, the polarization was found to be ∼13%, corresponding to an enhancement factor exceeding 16,000 relative to thermal polarization at 9.4 T and ambient temperature.
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Affiliation(s)
- Michael Batel
- Physical Chemistry, ETH Zürich, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland
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Armstrong BD, Edwards DT, Wylde RJ, Walker SA, Han S. A 200 GHz dynamic nuclear polarization spectrometer. Phys Chem Chem Phys 2010; 12:5920-6. [PMID: 20461268 DOI: 10.1039/c002290j] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present our experimental setup for both dynamic nuclear polarization (DNP) and electron paramagnetic resonance (EPR) detection at 7 T using a quasi-optical bridge for propagation of the 200 GHz beam and our initial results obtained at 4 K. Our quasi-optical bridge allows the polarization of the microwave beam to be changed from linear to circular. Only the handedness of circular polarization in the direction of the Larmor precession is absorbed by the electron spins, so a gain in effective microwave power of two is expected for circular vs. linear polarization. Our results show an increase in DNP signal enhancement of 28% when using circularly vs. linearly polarized radiation. We measured a maximum signal enhancement of 65 times that of thermal polarization for a (13)C labeled urea sample corresponding to 3% nuclear spin polarization. Since the time constant for nuclear spin polarization buildup during microwave irradiation is 10 times faster than the (13)C nuclear spin T(1), the actual gain in detection sensitivity with DNP is much greater.
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Maly T, Debelouchina GT, Bajaj VS, Hu KN, Joo CG, Mak–Jurkauskas ML, Sirigiri JR, van der Wel PCA, Herzfeld J, Temkin RJ, Griffin RG. Dynamic nuclear polarization at high magnetic fields. J Chem Phys 2008; 128:052211. [PMID: 18266416 PMCID: PMC2770872 DOI: 10.1063/1.2833582] [Citation(s) in RCA: 540] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dynamic nuclear polarization (DNP) is a method that permits NMR signal intensities of solids and liquids to be enhanced significantly, and is therefore potentially an important tool in structural and mechanistic studies of biologically relevant molecules. During a DNP experiment, the large polarization of an exogeneous or endogeneous unpaired electron is transferred to the nuclei of interest (I) by microwave (microw) irradiation of the sample. The maximum theoretical enhancement achievable is given by the gyromagnetic ratios (gamma(e)gamma(l)), being approximately 660 for protons. In the early 1950s, the DNP phenomenon was demonstrated experimentally, and intensively investigated in the following four decades, primarily at low magnetic fields. This review focuses on recent developments in the field of DNP with a special emphasis on work done at high magnetic fields (> or =5 T), the regime where contemporary NMR experiments are performed. After a brief historical survey, we present a review of the classical continuous wave (cw) DNP mechanisms-the Overhauser effect, the solid effect, the cross effect, and thermal mixing. A special section is devoted to the theory of coherent polarization transfer mechanisms, since they are potentially more efficient at high fields than classical polarization schemes. The implementation of DNP at high magnetic fields has required the development and improvement of new and existing instrumentation. Therefore, we also review some recent developments in microw and probe technology, followed by an overview of DNP applications in biological solids and liquids. Finally, we outline some possible areas for future developments.
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Affiliation(s)
- Thorsten Maly
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Galia T. Debelouchina
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Vikram S. Bajaj
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Kan-Nian Hu
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Chan-Gyu Joo
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | | | - Jagadishwar R. Sirigiri
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Patrick C. A. van der Wel
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Judith Herzfeld
- Department of Chemistry, Brandels University, Waltham, Massachusetts 02454, USA
| | - Richard J. Temkin
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert G. Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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