Characterization of Mass Spectra of Aluminum Anion ClustersGenerated by Laser Vaporization and Pulsed Molecular Beam Techniques

Aluminum anion clusters are generated by laser vaporization and molecular beam techniques. Mass abundance spectra exhibit a pronounced odd-even alternation for clusters ranging from
n = 5 to n = 17, which is related to the presence of trace oxygen and water resident in He carrier gas and explained by electron pairing effects. In addition, confirmation of jellium model predictions is revealed at peaked A1₁₃^-, and for the first time at Al₇O^-. A local maximum Al₇^- is also observed.