Increasing the spin-lattice relaxation time of hyperpolarized xenon ice at 4.2 K

摘要

After cryogenic trapping of hyperpolarized xenon produced by optical pumping, significant increases in the spin-lattice relaxation time (T_(1)) of ~(129)Xe in solid xenon at 4.2 K can be achieved by annealing the solid at an appropriate temperature. Thus, T_(1) at 4.2 K in a field of 180 G increased from 20.4 to 35 h on warming a sealed sample initially condensed at 77 K in an isopentane bath at 113 K for 10 min. This provides further confirmation that the primary relaxation mechanism for ~(129)Xe at low temperature is cross relaxation to ~(131)Xe and demonstrates that long term storage of hyperpolarized xenon produced using flow polarizers is feasible.