Magic numbers in Al-n(+)(H2O)(1) cluster cations

We report the observation of magic numbers in the mass spectrum of Al-n(+)( H2O)(1). These cluster cations were produced in a laser vaporization source in the presence of trace amounts of water. The most prominent magic number species observed was Al-13(+)(H2O)(1). We attribute its pronounced intensi ty to its enhanced stability resulting from the formation of a coordinate b ond between the Al-13(+) moiety and the oxygen atom of water. The sharing o f an oxygen lone electron pair with Al-13(+) lends to it some of the charac ter of the 40-valence electron, closed shell Al-13(-) magic cluster. (C) 19 99 Elsevier Science B.V. All rights reserved.