Optimal control pulses for the 1.2 GHz (28.2 T) NMR spectrometers

The ability to measure NMR spectra with a large sample volume is crucial for concentration limited biological samples in order to attain adequate signal-to-noise (S/N) ratio. The possibility to measure with a 5 mm cryoprobe is currently absent at the 1.2 GHz NMR instruments due to the exceedingly high radio frequency power demands, which is four times compared to a 600 MHz instruments. Here, we overcome the high power demands by designing optimal control (OC) pulses with up to 20 times lower power requirements than currently necessary at a 1.2 GHz spectrometer. We show that multidimensional biomolecular NMR experiments constructed using these OC pulses can bestow improvement in the S/N ratio of up to 26%. With the expected power limitations of a 5 mm cryoprobe, we observe an enhancement in the S/N ratio of more than 240% using our OC sequences. This motivates the development of a cryoprobe with a larger volume than the current 3 mm cryoprobes.