  We report the fabrication, characterization, and use of rubidium vapor
dispensers based on highly-oriented pyrolytic graphite (HOPG) intercalated with
metallic rubidium. Compared to commercial chromate salt dispensers, these
intercalated HOPG (IHOPG) dispensers hold an order of magnitude more rubidium
in a similar volume, require less than one-fourth the heating power, and emit
less than one-half as many impurities. Appropriate processing permits exposure
of the IHOPG to atmosphere for over ninety minutes without any adverse effects.
Intercalation of cesium and potassium into HOPG have also been demonstrated in
the literature, which suggests that IHOPG dispensers may also be be made for
those metals.
