A simple way to properly invert intense nuclear magnetization: application to laser-polarized xenon

The strong 129Xe NMR signal of laser-polarized samples may cause radiation damping in a high-resolution spectrometer, even if the sample is a low-pressure gas or dissolved xenon. This non-linear effect prevents proper inversion of the xenon polarization which is, however, required to safely detect the cross-relaxation between xenon and proton in SPINOE experiments. A quasi-perfect inversion profile is obtained by combining a field gradient pulse and a frequency-sweep adiabatic pulse (CHIRP pulse). This solution has the advantage of being not too affected by pulse miscalibration.