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NMR signals from diatomic alkali molecules have been observed in optically pumped cesium and rubidium vapors. The nuclear relaxation times were found to be strongly dependent on the temperature and buffer-gas pressure. The relaxation time seems to be determined by at least two and possibly three major factors: motional narrowing of the molecular hyperfine structure, breakup of the diatomic molecules by collisions with buffer-gas atoms, and possibly chemical exchange of free atoms with atoms bound in the molecules.Recently, Nienstadt et al} have used the chargeexchange method of Mitchell and Fortson 2 to make precision measurements of the Cs + NMR frequency in optically pumped cesium vapor. During the course of this work Nienstadt et al} noticed that NMR signals could still be observed even when no Cs + ions were intentionally produced in the vapor. They remarked that they "do not exclude the possibility that it [the signal] is associated with NMR in the Cs 2 molecule." We have observed similar NMR signals in optically pumped cesium and rubidium, and we present data which indicate that the signals do indeed originate in diatomic alkali molecules. The behavior of the molecules is strongly affected by the temperature and buffer-gas pressure, and these experiments afford a unique and simple way to observe simple gas-phase chemical reaction rates for a system in thermal equilibrium. These seem to be the first measurement of the formation and breakup rates of alkali molecules. The molecules also represent a new factor which must be taken into consideration when designing miniature optically pumped devices for operation at high temperature. 3 Our data were obtained with the apparatus sketched in Fig.

Bis-(2'-hydroxy-3'-methoxybenzylideneamino)-3,6dithiaoctane Cobalt(III) d-Antimonyl Tartrate Pentahydrate.-The ¿¿-iodide described above was suspended in water (150 ml.) and excess freshly precipitated silver chloride added. The mixture was then warmed to 50°and vigorously shaken for 20 minutes, after which the solids were filtered off and washed. The combined filtrate and washings (total volume 200 ml.) were then slowly treated with an almost saturated solution of potassium ¿-antimonyl tartrate (2.23 g.) in hot water, the sides of the container being scratched during the addition. Crystalline black prisms separated. These were collected and recrystallized several times from hot water to which a little potassium dantimonyl tartrate was added. The final crystalline product charred on heating.Anal. Caled, for Co(C22HMN204Sz)(C

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