As ion/ion afterglow plasma as a source of simple and clustered positive and negative ions

The development and mode of operation of a flowing afterglow (FA) plasma source of positive and negative ions are described. This source has been successfully used in conjunction with a selected ion flow tube (SIFT) as a source of simple and cluster ions (e.g. H30+(H20)sub(n)). It is shown that the ion current capability of the FA source is greatly enhanced by converting the positive-ion/electron afterglow plasma into a positive-ion/negative-ion afterglow plasma whence recombination and diffusive losses are greatly reduced. The chemical versatility of the source is stressed through several examples of its use and further possible applications are briefly discussed. (author)