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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. 

Abstract Signal Amplification by Reversible Exchange (SABRE) technique enables nuclear spin hyperpolarization of wide range of compounds using parahydrogen. Here we present the synthetic approach to prepare¹⁵N‐labeled [¹⁵N]dalfampridine (4‐amino[¹⁵N]pyridine) utilized as a drug to reduce the symptoms of multiple sclerosis. The synthesized compound was hyperpolarized using SABRE at microtesla magnetic fields (SABRE‐SHEATH technique) with up to 2.0 %¹⁵N polarization. The 7‐hour‐long activation of SABRE pre‐catalyst [Ir(IMes)(COD)Cl] in the presence of [¹⁵N]dalfampridine can be remedied by the use of pyridine co‐ligand for catalyst activation while retaining the¹⁵N polarization levels of [¹⁵N]dalfampridine. The effects of experimental conditions such as polarization transfer magnetic field, temperature, concentration, parahydrogen flow rate and pressure on¹⁵N polarization levels of free and equatorial catalyst‐bound [¹⁵N]dalfampridine were investigated. Moreover, we studied¹⁵N polarization build‐up and decay at magnetic field of less than 0.04 μT as well as¹⁵N polarization decay at the Earth's magnetic field and at 1.4 T.