Figure 7.

(a) ¹H NMR spectrum from a mixture containing d₄-methanol solvent, “recycled” NPCs, and the pyridine substrate thermally polarized at 9.4 T. (b) Corresponding ¹H (ex situ) HET-SABRE NMR spectrum obtained from the same sample of “recycled” NPCs, acquired immediately after 30 s of pH₂ bubbling at low field (∼100 G) and rapid transfer of the sample into the NMR magnet. All spectra shown were acquired with a single scan (90° pulse). Peaks at about δ ≈3.3 and ≈4.9 ppm are from residual protons from the deuterated methanol solvent. The peak at ≈4.5 ppm is from oH₂; broad peaks ∼1–2 ppm are primarily from the PMAA of the catalyst particles.