Sol-gel coated glass cells for spin-exchange polarized He3

We have developed a high-purity sol-gel coating for the interior surface of glass cells used for polarizing He3 by spin-exchange optical pumping. The coating is designed to minimize spin relaxation due to wall collisions. A longitudinal spin-relaxation time T1 in a sol-gel coated Pyrex cell of 344±8 h was achieved, the longest T1 we have ever recorded for a gaseous sample. Repeated trials indicated that the coating was quite robust. Results using an uncoated Pyrex cell were also quite good, although inferior to the performance of the coated cell.