Production of Hyperpolarized ¹²⁹Xe Gas Without Nitrogen by Optical Pumping at ¹³³Cs D₂ Line in Flow System

We report production of hyperpolarized ¹²⁹Xe gas via spin-exchange with optically pumped Cs atoms at the D₂ line, achieved at low magnetic field in a flow system and in the absence of nitrogen gas. The nuclear spin polarization of hyperpolarized ¹²⁹Xe gas is enhanced by a factor of 10000 compared to that without optical pumping under the same condition, which corresponds to polarization of about 2.66%. Due to the high spin polarization, the radiation damping of hyperpolarized ¹²⁹Xe gas has also been observed in the flow system.