Ionization Potentials and Electron Affinities of Semiconductor Clusters from Charge Transfer Reactions

Abstract

Ionization potentials (IPs) and electron affinities (EAs) are among the most important physical properties of small clusters. They can help to indicate both electronic and gross physical structure, if any, possessed by the clusters. Moreover, they can serve as one measure of the transition from individual atomic to bulk behavior. For several years, experiments at the University of Florida have employed Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry to study a number of gas phase ionic processes. The FT-ICR technique is the one mass spectrometry method best suited for obtaining both qualitative and quantitative information about ion/molecule reactions. FT-ICR mass spectrometry has been used to study cluster ions formed directly by laser desorption in the FT-ICR analyzer cell. Given the importance of ionization potentials and electron affinities in understanding cluster properties and given the power of FT-ICR to study ionic reactivities, such chemical reactivity studies of cluster ions, that is, their propensity to undergo charge transfer reactions, have been used to determine important physical properties of clusters. This chapter presents both advantages and disadvantages of the charge transfer bracketing approach.