Composite pulses in directly and indirectly detected14N MAS overtone spectroscopy.
14N MAS overtone spectroscopy is mainly limited by narrow excitation bandwidths owing to the use of very long pulses to get stronger signals. We previously reported the use of modified 90° composite pulses for broadband excitation in1H-{NOTDQ14}D-HMQC experiments at ultra-fast MAS. In this work, we modified the 180° composite pulses, which are originally designed for spin 1/2 nuclei, for both indirect detection in1H-{NOTDQ14}D-HMQC experiment and direct detection in one-pulse experiment, and found that the modified 180° composite pulses are useful for broadband excitation. Furthermore, we found that the bandwidth can be tailored by simply adjusting the total pulse length.
School of Physics and Materials Science, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China.
Ming
M
Shen
School of Physics and Materials Science, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China.
Qun
Q
Chen
School of Physics and Materials Science, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China. Electronic address: bwhu@phy.ecnu.edu.cn.
Bingwen
B
Hu
(14)N overtone spectroscopy; D-HMQC; Ultra-fast MAS