Laser ablation and gas-phase reactions of small gold cluster ions, Aun+ (1⩽n⩽7)

The abundance distributions of gold cations, Aun+ for 1⩽n⩽7, generated by pulsed laser ablation of gold metal were determined by time-of-flight mass spectrometry. The odd-n ions, Au3+, Au6+, and Au7+ were particularly abundant, consistent with previous results understood by rudimentary molecular orbital bonding models. A unique aspect of our experiment was the ability to enhance concentrations of the larger Aun+ by sampling slower ions in the tail of the ablation plume; this effect indicates ion formation under quasiequilibrium (high temperature) conditions. The primary goal of this study was to examine gas-phase reactions of Aun+ for n=1–7 by injecting a hydrocarbon or halocarbon into the ion trajectory and determining compositions/abundances of the resulting complex ions, Aun+-L, formed by abstraction of a ligand(s) L from the organic molecule(s). Among the more significant products were the carbides AunCc+, for n⩽7 and c⩽4. The Aun+-L products and distinctive n-dependent variations in product compositi...