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. Author manuscript; available in PMC: 2016 Sep 28.
Published in final edited form as: J Phys Chem B. 2014 Jan 24;118(12):3281–3290. doi: 10.1021/jp4102916

Figure 5.

Figure 5

15N NMR enhancement achieved in 15N-urea via heteronuclear polarization transfer from hyperpolarized water. Spectra were collected using a small flip-angle (9°) single-pulse irradiating on the 15N channel at 76 ppm, and acquiring 9 k data points (4 sec acquisition time). The dashed line is a fit to the two-site exchange model in eq. (3). The inset compares a single-scan DNP-enhanced 15N spectrum collected using a 90° pulse applied at an optimal post-injection delay of ≈40 sec, against a thermal equilibrium 15N NMR spectrum measured for the same sample by signal averaging 20 fully-relaxed scans, over a total of 13:50 hours. All measurements were done at 50 °C.