To enhance the NOT DQ1 4 sensitivity, its indirect detection was recently realized through 1H-{ } NOT DQ1 4 D-HMQC experiments [11,12]. A detailed comparison of different schemes for indirect detection of 14N signal can be found elsewhere [13]. However, as a matter of fact, NOT DQ1 4 spectroscopy is very sensitive to frequency offset, because the effective nutation frequency is very week for NOT DQ1 4 transition, and the maximum rf-field is usually less than ν14N¼75kHz. To attenuate the offset effects, a composite pulse ( ̅ 45135, referred to COM-V in this work) has first been applied for broadband excitation in NOT DQ1 4 spectroscopy under static condition [14]. Here, we investigate the performance of several composite pulses [15] for indirect detection through 1H-{ NOT DQ1 4 } D-HMQC experiments under MAS.
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Solid State Nuclear Magnetic Resonance
http://dx.doi.org/10.1016/j.ssnmr.2016.05.001 0926-2040/& 2016 Elsevier Inc. All rights reserved.
n Corresponding author. E-mail addresses: shen.ming@outlook.com (M. Shen)