Reactions of N2 with NinAl clusters, n=14–19, are used to determine the location of the Al atom within the cluster framework. N2 saturation levels are consistent with cluster structures in which one surface atom of the corresponding Nin+1 cluster is replaced with an Al atom. For n=14 and 17–19 it is possible to precisely locate the Al atom within the surface. In general, its placement maximizes the number of Ni–Al bonds for a surface Al atom.

The structures of NinAlp clusters of all compositions with n+p=12, 13, and 14 are studied both experimentally and theoretically. Experimental reactions of the clusters with N2 are used to determine the number of Ni atoms residing in the cluster surfaces. In agreement with the theoretical predictions, the N2 saturation levels are consistent with clusters having icosahedral and icosahedral-based structures. The various N2 adsorption channels seen in the experiment are explained in terms of the computed composition-dependent patterns of the configurational energies of the different structural forms.

Laser vaporization of an icosahedral Al-Pd-Mn sample with detection by time-of-flight mass spectrometry is used to probe metal clusters made from the alloy. After sample vaporization, clusters form by gas aggregation and may contain several to hundreds of atoms. Multi-photon ionization/fragmentation of these clusters yields mass spectra showing many cluster sizes with enhanced intensity. Clusters are identified at masses near those of pseudo- Mackay and Bergman clusters; however, these clusters do not appear special relative to neighboring clusters. Results of this study and its relationship to the proposed cluster structures in quasicrystalline materials are discussed.