Design of high-power, broadband 180° pulses and mixing sequences for fast MAS solid state chemical shift correlation NMR spectroscopy

An approach for the design of high-power, broadband 180° pulses and mixing sequences for generating dipolar and scalar coupling mediated 13 C– 13 C chemical shift correlation spectra of isotopically labelled biological systems at fast magic-angle spinning frequencies without 1 H decoupling during mixing is presented. Considering RF field strengths in the range of 100–120 kHz, as typically available in MAS probes employed at high spinning speeds, and limited B 1 field inhomogeneities, the Fourier coefficients defining the phase modulation profile of the RF pulses were optimised numerically to obtain broadband inversion and refocussing pulses and mixing sequences. Experimental measurements were carried out to assess the performance characteristics of the mixing sequences reported here.