ALUMINUM CLUSTER REACTIONS

Aluminum clusters, both anion and cation, are produced using laser vaporization and reacted under thermal conditions with oxygen in a flow tube reactor. An etching reaction is observed and bimolecular rate constants are reported for Al(n)+, n = 1-33, and Al(n)-, n = 5-37. For certain clusters, namely Al7+, Al13-, and Al23-, no apparent reactivity is observed (they are found to be produced from larger species). Interestingly, these correspond to predicted jellium shell closings with 20, 40, and 70 electrons, respectively. Besides these exceptions, and a small odd/even alternation in reaction rates, the overall reactivity is relatively insensitive to cluster size, and is found to range between about 1 X 10(-12) and 5 X 10(-12) cm3/s.