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

Abstract

A theoretical/computational description and analysis of the spectra of electron binding energies of Al12 –, Al13 –, 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.

Electron Binding Energy Spectra of AlnMo– Clusters: Measurements, Calculations, and Theoretical Analysis

“…This is particularly true when PES measurements are combined with theoretical/computational studies (cf. refs − and − and citations therein). This combination allows for characterization of: (1) electronic structure and geometric (isomeric) form, or forms, of a system generated under specific experimental conditions; (2) investigation of the changes in the electronic and geometric structure with the size of the system; and (3) exploration, in the case of nanoalloys, of the changes in the electronic structure and conformation (both isomeric and homotopic) of a system caused by adding or substituting some of its atoms by atoms of another element.…”

Predicting the Photoelectron Spectra of Quasi Octahedral Al6Mo‐ Cluster

“…[20]. As discussed in earlier work, [7,[9][10][11][12][13][14]20] this scheme is robust, accurate, and can be applied to any DFT exchange-correlation functional. The full scheme has been successfully applied to clusters and molecules.…”

“…The full scheme has been successfully applied to clusters and molecules. [7,[9][10][11][12][13][14] We have shown in ref. [16] that this methodology reproduces well the PES of Al n Mo -, n = 3-5,7.…”

“…Adding a single metallic impurity to a pure metal cluster can have important effects such as increasing/decreasing their reactivity or enhancing/ suppressing their magnetism. An excellent example of how dramatic these effects can be found in our recent work [14] on the explanation the evolution of the photoelectron spectra (PES) from a 12 atom pure aluminum cluster to the 13 atom Al 13 and Al 12 Niclusters. The addition of an Al or Ni atom leads to substantially different spectra and we were able to separate the different effects of size, structure, symmetry, and composition.…”

“…Another example is our work on mixed anionic aluminum-molybdenum clusters [16] where we applied the analysis developed in ref. [14] to explain the measured spectrum of Al n Mo -, n = 3-5,7 and to separate the effects of size, symmetry, composition to explain the changes in spectrum of Al 4 -, Al 5 -, and Al 4 Mo -.…”