Fig. 2: Time dependence of the zero-field NMR signal of SABRE-polarized pyridine.
From: Detection of pyridine derivatives by SABRE hyperpolarization at zero field
a Zero-field spectrum of SABRE-polarized 15N-pyridine during prolonged para-hydrogen bubbling. The NMR signal amplitude increases as the SABRE catalyst activates (the spectra were shifted in the vertical direction for better visibility). b Signal intensity (red points) as a function of time the precatalyst was exposed to pH2 (the nonzero initial response indicates the sample was partially activated at measurement onset). Darker, shaded data points correspond to the NMR spectra shown in part (a). Analogous signal-intensity profile (blue points) is shown for a sample that was fully activated prior to the measurements. The signal high reproducibility, with 2.3% variation in signal intensity over hundreds of transients, is demonstrated. To facilitate these measurements, a 70 mM solution of labelled [15N]-pyridine was used to boost the zero-field signal.
