Coherent Dynamic Nuclear Polarization using Chirped Pulses

Abstract

This paper presents a study of coherent dynamic nuclear polarization (DNP) using frequency swept pulses at 94 GHz which optimize the polarization transfer efficiency. Accordingly, an enhancement ε ∼ 496 was observed using 10 mM trityl-OX063 as the polarizing agent in a standard 6:3:1 d 8 -glycerol/D 2 O/H 2 O glassing matrix at 70 K. At present, this is the largest DNP enhancement reported at this microwave frequency and temperature. Furthermore, the frequency swept pulses enhance the nuclear magnetic resonance (NMR) signal and reduce the recycle delay, accelerating the NMR signal acquisition.

Triplet dynamic nuclear polarization of pyruvate via supramolecular chemistry

“…In addition, the implementation of more advanced polarization transfer methods with field/frequency modulation would improve the final spin polarization. 67,68 Hyperpolarized MRI with triplet-DNP will be possible by combining the optimized molecular design of polarizing agents with the key finding of the present study that supramolecular complexation is useful to hyperpolarize NaPyr at high concentrations.…”

Frequency-Chirped Magic Angle Spinning Dynamic Nuclear Polarization Combined with Electron Decoupling

“…Pulsed DNP methods provide a promising approach to improve sensitivity at high magnetic fields. − However, pulsed DNP at high magnetic field requires very high power microwaves and short pulses, not achievable with present technology. Compared to pulsed DNP methods that impose such strict requirements on the microwave source, chirped DNP can utilize more accessible broadband frequency-modulated microwave sources to increase DNP efficiency over CW DNP at high magnetic fields. ,− Most microwave frequency-modulated DNP experiments have been performed under static conditions, ,− with a few examples demonstrating chirped DNP under MAS. − …”