M.S.

The pure quadrupole resonant frequency dependence on temperature of the Br⁷⁹ isotope was examined from 4.2°K to 346°K. These data were fitted with the Bayer theory as extended by Kushida. The inequality of the two assumed modes of bromate-group vibration as well as the possibility of temperature dependence associated with these bromate-group vibrations were considered. Results indicate that a temperature dependence of the bromate-group vibrations must be included for temperature regions larger than 4.2°K to 100°K. A greater temperature range is necessary in order to determine ·whether or not the t wo assumed modes of bromate-group vibration are equal. / M.S.