Parahydrogen‐Induced Carbon‐13 Radiofrequency Amplification by Stimulated Emission of Radiation
Christopher Nelson, Andreas B. Schmidt, Isaiah Adelabu, Shiraz Nantogma, Valerij G. Kiselev, Abubakar Abdurraheem, Henri de Maissin, Sören Lehmkuhl, Stephan Appelt, Thomas Theis, Eduard Y. Chekmenev
Abstract
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‐ 13 C]acetate. Hyperpolarized ethyl [1‐ 13 C]acetate was prepared via pairwise addition of parahydrogen to vinyl [1‐ 13 C]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.