Xe-129 Nmr - Highly Polarized Thin Films

We studied the macroscopic effects of nuclear magnetization. Highly polarized xenon is often used to increase the sensitivity in NMR investigations of porous media, diluted liquids or for imaging in the gas phase. In the condensed phase, however, highly nuclear spin polarized xenon also possesses a sizable magnetization due to the nuclear spin density. This results in an additional magnetic field, that is used to measure the polarization of the sample, when only the particle density is known. Here we find P-z approximate to 0.8 corresponding to a spin temperature of 0.5 mK. We use isotopically enriched xenon with a Xe-129 abundance of 0.71. At high abundance of Xe-129 and high nuclear polarization the dipolar linewidth is considerably reduced. We find for small angle excitation a reduction from 650 Hz to 400 Hz. We investigate this using a thin film geometry. The susceptibility effects of the substrate and the Xe film are treated. The macroscopic angle between the normal of the film and the external field strongly changes the polarization induced line shift and line width. The first follows an expected cos(2) theta dependence with an understood amplitude the latter however is not understood up to now. Relaxation of Xe-129 in the condensed film is observed to be T-1 = 15 +/- 1.8 min, much faster than expected. (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.