Theoretical Analysis of Photoelectron Spectra of Pure and Mixed Metal Clusters: Disentangling Size, Structure, and Composition Effects

A theoretical/computational description and analysis of the spectra of electron binding energies of Al-12(-), Al-13(-), and Al12Ni- clusters, which differ in size and/or composition by a single atom yet possess strikingly different measured photoelectron spectra, is presented. It is shown that the measured spectra can not only be reproduced computationally with quantitative fidelity-this is achieved through a combination of state-of-the-art density functional theory with a highly accurate scheme for conversion of the Kohn-Sham eigenenergies into electron binding energies but also explained in terms of the effects of size, structure/symmetry; and composition. A new methodology is developed and applied that provides for disentanglement and differential assignment of the separate roles played by size, structure/symmetry, and composition in defining the observed differences in the measured spectra. The methodology is general and applicable to any finite system, homogeneous or heterogeneous. We project that in combination with advances in synthesis techniques this, methodology will become an indispensable computation-based aid in the design of controlled synthesis protocols for manufacture of nanosystems and nanodevices with precisely desired electronic and other characteristics.