SORDOR pulses: expansion of the Böhlen–Bodenhausen scheme for low-power broadband magnetic resonance

<p>A novel type of efficient broadband pulse, called second-order phase dispersion by optimised rotation (SORDOR), has recently been introduced. In contrast to adiabatic excitation, SORDOR-90 pulses provide effective transverse 90<span class="inline-formula">^∘</span> rotations throughout their bandwidth, with a quadratic offset dependence of the phase in the <span class="inline-formula"><i>x</i>,<i>y</i></span> plane. Together with phase-matched SORDOR-180 pulses, this enables the Böhlen–Bodenhausen broadband refocusing approach for linearly frequency-swept pulses to be extended to any type of 90<span class="inline-formula">^∘</span>/180<span class="inline-formula">^∘</span> pulse–delay sequence. Example pulse shapes are characterised in theory and experiment, and an example application is given with a <span class="inline-formula">¹⁹F</span>-PROJECT experiment for measuring relaxation times with reduced distortions due to <span class="inline-formula"><i>J</i></span>-coupling evolution.</p>