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 negative ions (La--Lu-) have been observed except Pm-, Ho-, and Er-. The heavy element analysis line at the IsoTrace 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. Because of its very low electron affinity, Dy- had a terminal voltage dependent yield, and its study required the reduction of the electric field gradients used to accelerate the ions. The relative negative ion yields among the lanthanides will be discussed. Both Yb-and Lu- have recently been theoretically predicted to exist in negative parity ground states. (orig.)