Sol-gel coated glass cells for spin-exchange polarized He-3

We have developed a high-purity sol-gel coating for the interior surface of glass cells used for polarizing He-3 by spin-exchange optical pumping. The coating is designed to minimize spin relaxation due to wall collisions. A longitudinal spin-relaxation time T-1 in a sol-gel coated Pyrex cell of 344 +/- 8 h was achieved, the longest T-1 we have ever recorded for a gaseous sample. Repeated trials indicated that the coating was quite robust. Result s using an uncoated Pyrex cell were also quite good, although inferior to t he performance of the coated cell. (C) 2000 American Institute of Physics. [S0003-6951(00)02839-4].