RADIUM, ACTINIDES, AND THEIR MOLECULAR NEGATIVE-IONS FROM A CESIUM SPUTTER ION-SOURCE

The negative ions of the isotopes Ra-226, Pa-231 and Pu-244, produced by a Cs sputter ion source, have been observed for the first time usin g the IsoTrace heavy element AMS system. The properties of these negat ive ions have been compared with those of Th and U, and the electron a ffinities of all these elements (Ra, Th, Pa, Th and Pu) have been foun d to be similar and greater than 50 meV. Some molecular negative ions of these elements, in particular carbides and oxides, have also been m easured. It was found that di-carbide is generally a profitable molecu le form for measuring Ra, Th and Pa, while mono-oxide is more efficien t for measuring U and Pu.