Indexed on: 09 Feb '07Published on: 09 Feb '07Published in: The European Physical Journal D
We studied the free precession of the nuclear magnetization of hyperpolarized 129Xe gas in external magnetic fields as low as B0 = 4.5 nT, using SQUIDs as magnetic flux detectors. The transverse relaxation was mainly caused by the restricted diffusion of 129Xe in the presence of ambient magnetic field gradients. Its pressure dependence was measured in the range from 30 mbar to 850 mbar and compared quantitatively to theory. Motional narrowing was observed at low pressure, yielding transverse relaxation times of up to 8000 s.