Parahydrogen‐Induced Radio Amplification by Stimulated Emission of Radiation

Abstract

Radio amplification by stimulated emission of radiation (RASER) was recently discovered in al ow-field NMR spectrometer incorporating ah ighly specialized radiofrequency resonator,w here ah igh degree of proton-spin polarization was achieved by reversible parahydrogen exchange.R ASER activity,w hichr esults from the coherent coupling between the nuclear spins and the inductive detector, can overcome the limits of frequency resolution in NMR. Here we show that this phenomenon is not limited to low magnetic fields or the use of resonators with high-quality factors.W euse ac ommercial bench-top 1.4 TNMR spectrometer in conjunction with pairwise parahydrogen addition producing protonhyperpolarized molecules in the Earthsm agnetic field (AL-TADENAc ondition) or in ah igh magnetic field (PASADE-NA condition) to induce RASER without any radio-frequency excitation pulses.The results demonstrate that RASER activity can be observed on virtually any NMR spectrometer and measures most of the important NMR parameters with high precision.

Scanning Nuclear Spin Level Anticrossings by Constant-Adiabaticity Magnetic Field Sweeping of Parahydrogen-Induced 13C Polarization

“…Also, the HP protons readily establish radio amplification by stimulated emission of radiation (RASER) at high concentrations and high P values, making the precise P H measurement challenging under the experimental conditions. − For a hydrogenation duration of 8 s, we estimate that P H is ∼16–24% in the studied spin system, corresponding to the estimateed polarization transfer efficiency of ∼50%, in line with the polarization transfer efficiency measured by Ivanov and coworkers …”

Clinical-Scale Production of Nearly Pure (>98.5%) Parahydrogen and Quantification by Benchtop NMR Spectroscopy

“…Last, we demonstrate the utility of the p -H 2 generator reported here for creating of parahydrogen-induced radio amplification by stimulated emission of radiation (PHIP-RASER) effect. ,, Parahydrogen was bubbled for 10 s into a solution containing ∼200 mM ethyl vinyl substrate and 4 mM Rh-based hydrogenation catalyst in CD 3 OD at Earth’s magnetic field (Figure a) . This experiment resulted in a proton polarization of 8.4% (reference signal of thermally polarized ethyl 1- 13 C-acetate (EA-1- 13 C), Figure c,b.…”

“…Generator utility for parahydrogen-induced polarization experiments was demonstrated in a wide range of PHIP and SABRE studies since the commencement of this device in March 2019. ,− …”

RASER MRI: Magnetic resonance images formed spontaneously exploiting cooperative nonlinear interaction

“…In addition, multimode RASER activity gives insight into fundamental phenomena in nonlinear mathematics (14) and synergetics (15) such as line collapse, multiple-period doubling, intermittence, and chaos (4,12,16). Most recently, the parahydrogen (p-H 2 ) pumped (17,18) RASER has been established (12,16,(19)(20)(21), by creating strong population inversions directly in room-temperature solutions. RASER magnetic resonance imaging (MRI) is associated with an alternative contrast mechanism than standard MRI, and it appears natural to wonder whether it could serve as a means to overcome fundamental limits of Lorentzian-based point spread functions (PSFs) in MRI (22,23).…”