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Abstract The feasibility of Carbon‐13 Radiofrequency (RF) Amplification by Stimulated Emission of Radiation (C‐13 RASER) is demonstrated on a bolus of liquid hyperpolarized ethyl [1‐13C]acetate. Hyperpolarized ethyl [1‐13C]acetate was prepared via pairwise addition of parahydrogen to vinyl [1‐13C]acetate and polarization transfer from nascent parahydrogen‐derived protons to the carbon‐13 nucleus via magnetic field cycling yielding C‐13 nuclear spin polarization of approximately 6 %. RASER signals were detected from samples with concentration ranging from 0.12 to 1 M concentration using a non‐cryogenic 1.4T NMR spectrometer equipped with a radio‐frequency detection coil with a quality factor (Q) of 32 without any modifications. C‐13 RASER signals were observed for several minutes on a single bolus of hyperpolarized substrate to achieve 21 mHz NMR linewidths. The feasibility of creating long‐lasting C‐13 RASER on biomolecular carriers opens a wide range of new opportunities for the rapidly expanding field of C‐13 magnetic resonance hyperpolarization.
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Through-bond and through-space radiofrequency amplification by stimulated emission of radiation
Abstract Radio Amplification by Stimulated Emission of Radiation (RASER) is a phenomenon observed during nuclear magnetic resonance (NMR) experiments with strongly negatively polarized systems. This phenomenon may be utilized for the production of very narrow NMR lines, background-free NMR spectroscopy, and excitation-free sensing of chemical transformations. Recently, novel methods of producing RASER by ParaHydrogen-Induced Polarization (PHIP) were introduced. Here, we show that pairwise addition of parahydrogen to various propargylic compounds induces RASER activity of other protons beyond those chemically introduced in the reaction. In high-field PHIP, negative polarization initiating RASER is transferred via intramolecular cross-relaxation. When parahydrogen is added in Earth’s field followed by adiabatic transfer to a high field, RASER activity of other protons is induced via bothJ-couplings and cross-relaxation. This through-bond and through-space induction of RASER holds potential for the ongoing development and expansion of RASER applications and can potentially enhance spectral resolution in two-dimensional NMR spectroscopy techniques.
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- Award ID(s):
- 1904780
- PAR ID:
- 10549234
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Communications Chemistry
- Volume:
- 7
- Issue:
- 1
- ISSN:
- 2399-3669
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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