First observation of excited states in [sup 199]At with the recoil filter detector

We have deduced for the first time a level scheme for the {sup 199}At nucleus. The angular distribution data and the conversion electron information have allowed for multipolarity assignments and spin suggestions to be made. The current data and the level systematics of odd At isotopes suggest that the first excited state should be isomeric with a lifetime of the order of a microsecond.