In multidimensional solution NMR experiments, π pulses are used extensively for inversion and refocusing operations on 1H, 13C and 15N nuclei. Pulse miscalibration, off-resonance effects, and J-coupling evolution during π pulse execution result in severe signal losses that are exacerbated at high magnetic fields. Here, we report the implementation of a triply-compensated π pulse (G5) optimized for both inversion and refocusing in widely used 2- and 3-dimensional experiments. By replacing most of the hard π pulses, adiabatic or composite pulses on the 1H, 13C and 15N channels with G5 pulses, we obtained signal enhancements ranging from 80 to 240%. We anticipate that triply-compensated pulses will be crucial for improving the performance of multidimensional and multinuclear pulse sequences at ultra-high fields.
Bibliographical noteFunding Information:
Acknowledgements This work is financially supported by the National Institute of Health (GM 100310 to G.V. and AI094623 to C.G.K.). The experiments were carried out at the Minnesota NMR Center (MNMR).
© 2017, Springer Science+Business Media B.V., part of Springer Nature.
- Genetic algorithm
- Off-resonance effects
- Sensitivity enhancement
- Triply compensated pulses (G5)
- Universal inversion and refocusing pulses