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. Author manuscript; available in PMC: 2012 Sep 1.
Published in final edited form as: Solid State Nucl Magn Reson. 2011 Aug 6;40(2):31–41. doi: 10.1016/j.ssnmr.2011.08.001

Figure 2.

Figure 2

(a) Illustrative pulse sequence for a general DNP-NMR SSNMR experiment. The saturation prior to the experiment ensures the same initial NMR signals regardless of the microwave irradiation mode, which is either continuous or intermittent for NMR pulsing and detection periods. (b) Typical DNP buildup under MAS conditions, such as the results shown for polarized 13C-urea signals from DNP using BT2E in d6- DMSO/D2O/H2O (6:3:1 w/w/w) at 90 K and 5 T. The enhancement factor was assessed by comparing NMR signals with and without microwave irradiation and showed little dependence on microwave irradiation time under MAS. (c) The DNP buildup time constant was similar to T1n because the polarizing agents were well-diluted against the concentration of bulk protons. Figures are reprinted from [22*].