LANTHANIDE NEGATIVE-ION DETECTION USING ACCELERATOR MASS-SPECTROMETRY

Accelerator mass spectrometric methods have been used in the detection of the negative ions of the lanthanides. All of the lanthanide negati ve ions (La--Lu-) have been observed except Pm-, Ho-, and Er-. The hea vy element analysis line at the Isotrate Laboratory was used to count the positive ions resulting from the atomic negative ions produced in a Cs sputter ion source and passed through the tandem accelerator. Bec ause of its very low electron affinity, Dy had a terminal voltage depe ndent yield, and its study required the reduction of the electric fiel d gradients used to accelerate the ions. The relative negative ion yie lds among the lanthanides will be discussed. Both Yb- and Lu- have rec ently been theoretically predicted to exist in negative parity ground states.