ALKALI REACTIONS WITH WALL COATING MATERIALS USED IN ATOMIC RESONANCE CELLS

J.C. Camparo, R.P. Frueholz, B. Jaduszliwer

Abstract:	In certain atomic frequency standards it is necessary to inhibit the relaxation of atomic polarization induced by collisions between polarized species and the walls of the storage cell. It is well known that the chemisorption of various chlorosilane materials on glass atomic storage vessel walls results in surface coatings which inhibit electronic and nuclear spin relaxation. In the present study the chemical reaction of rubidium, and by analogy other alkali metals, with dichlorod methylsilane-treated glass surfaces has been studied. We find evidence that rubidium reacts with a freshly prepared coating to produce H, and a volatile silicon-containing species. The most reasonable reaction process is postulated to be rubidium reacting with residual silanol groups (Si-OH) found on the surface. As the reaction proceeds these groups would disappear, thus reducing the spin relaxation rate associated with the surface. We believe that this reaction results in the "curing" of wall coatings reported by other investigators. Concurrently, the gaseous reaction products become impurities within the system. The spin relaxation cross section of the silicon containing species is expected to be less than 1 x 10-17 cm.
Published in:	Proceedings of the 19th Annual Precise Time and Time Interval Systems and Applications Meeting December 1 - 3, 1989 Sheraton Hotel Redondo Beach, California
Pages:	255 - 266
Cite this article:	Camparo, J.C., Frueholz, R.P., Jaduszliwer, B., "ALKALI REACTIONS WITH WALL COATING MATERIALS USED IN ATOMIC RESONANCE CELLS," Proceedings of the 19th Annual Precise Time and Time Interval Systems and Applications Meeting, Redondo Beach, California, December 1987, pp. 255-266.
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