Enhancing cross-peak intensity in 2D-SLF spectroscopy – The role of equilibrium carbon magnetization in cross-polarization experiment

A modification to the standard Hartmann–Hahn cross-polarization experiment has been proposed in which the initial 90° pulses are applied both on the I and S spins. The inclusion of the available equilibrium polarization in the static magnetic field for the S spins is shown to have a beneficial effect for the 2D-SLF experiment, contributing to an increase in the cross-peak intensity and hence to a better resolution of the dipolar cross-peaks.