Figure 9.

Experimental ¹³C spectra of microcrystalline ubiquitin spinning at 12 kHz to demonstrate the action of (a) single hard pi pulses and (b) GA optimized pi pulses of length 5π. The experiments were performed at two different power levels to show the advantage of GA optimized π pulses. The black spectra are with power level 60 W, which is the calibrated power for π pulse of length 12.5 μs. The red spectra are with power level 90 W. In 700 MHz spectrometer, irradiating at the 116 ppm (of ¹³C), the chemical shift offset CO and Ca were ~±10 kHz away from the resonance. GA pulses shows near uniform performance for both power levels. This demonstrates robust performance of GA pulses in presence of RF inhomogeneity/pulse calibration errors along with an offset of ~±10 kHz.