First observation and mobility measurements of negative ions in superfluid 4He

We present the results of the first mobility measurements in superfluid helium for negative ions of different elements. Various negative ions like Cl-, F- and I- were produced by laser ablation from targets consisting of NaCl, NaF, NaI, LiF and KCl immersed in a He-4 bath. In addition to negative ions of halogen ablated from salts we have studied the mobility of the negative metallic ions Ba- and Ga- implanted into superfluid helium. (C) 2003 Elsevier Science B.V. All rights reserved.