Multiply negatively charged aluminium clusters II.

Earlier experiments [Eur. Phys. J. D 43, 241 (2007)] investigating the production of aluminium cluster dianions have been extended to larger cluster sizes for the purpose of producing higher charge states. Polyanions are produced using the “electron-bath technique" which involves the exposure of monoanionic clusters to a bath of low-energy secondary electrons. In this contribution the production of Aln3- is investigated as a function of cluster size. Relative trianion yields (number of trianions produced relative to the number of precursor anions) were observed to increase from a few percent up to 55% within ~30 cluster sizes. The observed appearance size (n = 103) is in reasonable agreement with the predictions of classical models