Three pairs of radioactive tellurium isomers have been studied with the help of a chemical method for separating the isomers. In the case of each pair of isomers it was found that the longer-lived activity constitutes an isomeric transition from an upper to a lower level in the tellurium nucleus, and that the shorter-lived activity is due to beta-particle decay from the lower level to an iodine isotope. It has been possible to make isotopic assignments for these three pairs of isomers and also for a seventh (single) tellurium activity. The data are collected in the following table:

• Received 21 December 1939

DOI:https://doi.org/10.1103/PhysRev.57.363