Time-resolved optical nuclear polarization by rapid field switching

Tycko, Robert; Pines, Alexander; Stehlik, D.

doi:10.1016/0009-2614(82)83716-0

Cited by 10 publications

(10 citation statements)

References 11 publications

(11 reference statements)

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“…The optimum field value thus depends on the exact ZFS parameters and crystalline sample orientation with respect to B 0 . Rapid B 0 switching away from the LAC after a laser pulse can increase polarization levels …”

Section: Hyperpolarization Techniquesmentioning

confidence: 99%

“…Rapid B 0 switching away from the LAC after a laser pulse can increase polarization levels. 600 In tDNP, B 0 is usually chosen to set the system away from a LAC, and the transfer of electron polarization to nuclei is mediated by application of a MW (or RF) field. Since EPR spectra are broadened inhomogeneously 601,602 (Figure 70), CW MW irradiation affects only a small fraction of electron spins and is thus less efficient compared to pulsed MW irradiation.…”

Section: Chemical Reviewsmentioning

confidence: 99%

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Spin Hyperpolarization in Modern Magnetic Resonance

et al. 2023

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Magnetic resonance techniques are successfully utilized in a broad range of scientific disciplines and in various practical applications, with medical magnetic resonance imaging being the most widely known example. Currently, both fundamental and applied magnetic resonance are enjoying a major boost owing to the rapidly developing field of spin hyperpolarization. Hyperpolarization techniques are able to enhance signal intensities in magnetic resonance by several orders of magnitude, and thus to largely overcome its major disadvantage of relatively low sensitivity. This provides new impetus for existing applications of magnetic resonance and opens the gates to exciting new possibilities. In this review, we provide a unified picture of the many methods and techniques that fall under the umbrella term "hyperpolarization" but are currently seldom perceived as integral parts of the same field. Specifically, before delving into the individual techniques, we provide a detailed analysis of the underlying principles of spin hyperpolarization. We attempt to uncover and classify the origins of hyperpolarization, to establish its sources and the specific mechanisms that enable the flow of polarization from a source to the target spins. We then give a more detailed analysis of individual hyperpolarization techniques: the mechanisms by which they work, fundamental and technical requirements, characteristic applications, unresolved issues, and possible future directions. We are seeing a continuous growth of activity in the field of spin hyperpolarization, and we expect the field to flourish as new and improved hyperpolarization techniques are implemented. Some key areas for development are in prolonging polarization lifetimes, making hyperpolarization techniques more generally applicable to chemical/biological systems, reducing the technical and equipment requirements, and creating more efficient excitation and detection schemes. We hope this review will facilitate the sharing of knowledge between subfields within the broad topic of hyperpolarization, to help overcome existing challenges in magnetic resonance and enable novel applications.

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Section: Hyperpolarization Techniquesmentioning

confidence: 99%

Section: Chemical Reviewsmentioning

confidence: 99%

Spin Hyperpolarization in Modern Magnetic Resonance

et al. 2023

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“…Filed-cycling by sample shuttling has been reported in papers on zero-field NMR and nuclear quadruple resonance, [23][24][25][26] nuclear-spin relaxation studies, [27][28][29] coherence transfer in chemically induced dynamic nuclear polarization, 30 and ONP. 17,[31][32][33][34] As schematically shown in Fig. 2, a split-electromagnet and a solenoidal superconducting magnet ͑SCM͒ are employed for DNP and NMR measurement, between which the sample is shuttled.…”

Section: Magnetic-field Cycling Instrumentation For Dynamic Nuclear Polarization-nuclear Magnetic Resonance Using Photoexcited Tripletsmentioning

confidence: 99%

Magnetic-field cycling instrumentation for dynamic nuclear polarization-nuclear magnetic resonance using photoexcited triplets

Kagawa

Negoro

Takeda

et al. 2009

Review of Scientific Instruments

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To advance static solid-state NMR with hyperpolarized nuclear spins, a system has been developed enabling dynamic nuclear polarization (DNP) using electron spins in the photoexcited triplet state with X-band microwave apparatus, followed by static solid-state nuclear magnetic resonance (NMR) experiments using the polarized nuclear-spin system with a goniometer. In order to perform the DNP and NMR procedures in different magnetic fields, the DNP system and the NMR system are spatially separated, between which the sample can be shuttled while its orientation is controlled in a reproducible fashion. We demonstrate that the system developed in this work is operational for solid-state NMR with hyperpolarized nuclear-spin systems in static organic materials, and also discuss the application of our system.

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“…Today, the most common optical nuclear polarization methods in solids harness the electron spin polarization in the excited triplet state of a chromophore, using gated microwave irradiation, fast magnetic field sweeps, and/or low-field level anti-crossing (LAC) matching conditions to transfer the electron spin polarization to nearby nuclear spins. ,,− These optical hyperpolarization techniques are typically performed in single crystals, as they require alignment of the chromophore molecular frame with respect to the applied magnetic field because of the strong orientation dependence of the triplet zero-field splitting. Consequently, it is extremely challenging to generate optical nuclear polarization if the target cannot be formulated as a single crystal, although one example of 1 H hyperpolarization has been observed in pentacene-doped polycrystalline naphthalene under microwave irradiation and magnetic field sweeping …”

Section: Introductionmentioning

confidence: 99%

Optically Enhanced Solid-State ¹H NMR Spectroscopy

et al. 2023

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Low sensitivity is the primary limitation to extending nuclear magnetic resonance (NMR) techniques to more advanced chemical and structural studies. Photochemically induced dynamic nuclear polarization (photo-CIDNP) is an NMR hyperpolarization technique where light is used to excite a suitable donor–acceptor system, creating a spin-correlated radical pair whose evolution drives nuclear hyperpolarization. Systems that exhibit photo-CIDNP in solids are not common, and this effect has, up to now, only been observed for 13C and 15N nuclei. However, the low gyromagnetic ratio and natural abundance of these nuclei trap the local hyperpolarization in the vicinity of the chromophore and limit the utility for bulk hyperpolarization. Here, we report the first example of optically enhanced solid-state 1H NMR spectroscopy in the high-field regime. This is achieved via photo-CIDNP of a donor–chromophore–acceptor molecule in a frozen solution at 0.3 T and 85 K, where spontaneous spin diffusion among the abundant strongly coupled 1H nuclei relays polarization through the whole sample, yielding a 16-fold bulk 1H signal enhancement under continuous laser irradiation at 450 nm. These findings enable a new strategy for hyperpolarized NMR beyond the current limits of conventional microwave-driven DNP.

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Time-resolved optical nuclear polarization by rapid field switching

Cited by 10 publications

References 11 publications

Spin Hyperpolarization in Modern Magnetic Resonance

Spin Hyperpolarization in Modern Magnetic Resonance

Magnetic-field cycling instrumentation for dynamic nuclear polarization-nuclear magnetic resonance using photoexcited triplets

Optically Enhanced Solid-State ¹H NMR Spectroscopy

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Time-resolved optical nuclear polarization by rapid field switching

Cited by 10 publications

References 11 publications

Spin Hyperpolarization in Modern Magnetic Resonance

Spin Hyperpolarization in Modern Magnetic Resonance

Magnetic-field cycling instrumentation for dynamic nuclear polarization-nuclear magnetic resonance using photoexcited triplets

Optically Enhanced Solid-State 1H NMR Spectroscopy

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Product

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Optically Enhanced Solid-State ¹H NMR Spectroscopy