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

The strong Xe-129 NMR signal of laser-polarized samples may cause radiation damping in a high-resolution spectrometer, even if the sample is a low-pre ssure gas or dissolved xenon. This non-linear effect prevents proper invers ion of the xenon polarization which is, however, required to safely detect the cross-relaxation between xenon and proton id SPINOE experiments. A quas i-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. (C) 1999 Else vier Science B.V. All rights reserved.