By ensuring that the total amplitude of all pulses fired simultaneously stays within the linear region, distortions to pulse shapes should be minimised. This must be balanced against the desire for short pulse lengths, which both increase signal intensity and minimise evolution under the influence of 𝐻 9 ( during pulses. We decided to use 80 ns 180° pulses, which were attainable with 20% amplitude at both 𝜈 ) and 𝜈 * . The total amplitude of both pulses when fired simultaneously is then 40%, which is very close to, if not within, the linear response regime.