Optimal control pulses for Bloch-Siegert shift free NMR experiments

Compensating frequency shift due to Bloch-Siegert shift is essential for real-time decoupling of carbon detected NMR experiments. Here we develop symmetric three-band optimal control pulses that achieve robust compensation. We observe up to 83% signal-to-noise enhancement using an Optimal Control Band-Selective Homonuclear Decoupling (O-BASHD) scheme. Systematic evaluation reveals that optimal control pulse strategies significantly outperform existing techniques for homonuclear decoupling of carbon spins, reducing experiment time up to six fold. We demonstrate the generality of the approach by successfully applying it to both liquid-state and solid-state NMR experiments on challenging samples, using instruments ranging from 600 MHz to 1.2 GHz.