We controlled the pulse amplitude using an Arbitrary Waveform Generator (AWG) over its whole range (parameterised as 0 to 100%). Our experimental setup shows a linear relationship between amplitude and nutation frequency up to a pulse amplitude of 30% (Figure ). The linear regime may extend above 30%, but a precise determination of the upper limit was not possible between 30% and 60% due to strong nuclear ESEEM oscillations caused by hyperfine coupling to 1 H nuclei in the protonated solvent matrix.