Photoelectron Spectroscopy Meets Aqueous Solution: Studies from a Vacuum Liquid Microjet

Abstract

Characterization of the structure and properties of matter would be incomplete without the detailed knowledge of electronic structure, and yet, for aqueous solutions, not even the binding energies of the valence electrons are generally known. Thus, fundamental interactions between solute electronic structure and water, essentially the key to chemical reactivity, have remained poorly understood. This work describes how, by the development of the vacuum liquid microjet technique for X-ray photoelectron spectroscopy, electronic structure measurements from aqueous solutions have advanced to date. Direct and resonant second-order electron emission processes are discussed in light of the specific electron structure information accessible from aqueous solutions. Several examples of solutes in their natural aqueous environment will be presented along with future research directions and prevailing challenges in the field.