We produced gaseous hydrated clusters of sulfate and oxalate anions {SO42(H2O)n and C2 O42(H2,O)n (n=4-40)]. Photoelectron spectra (PES) of these clusters revealed that the solute dianions were in the center of the water cluster, (H2O)n. For small clusters, the PES were characteristic of the respective solutes, but beyond the first solvation shell (n=12), features in the PES from the solutes were diminished and a new feature from ionization of water emerged, analogous to bulk aqueous solutions. For large clusters with dimensions over one nanometer, the solute photoemission features disappeared and the PES were dominated by the ionization of water as the solvent coverage increased. A smooth transition from gas-phase clusters to behavior of electrolyte solutions was clearly revealed, and the large solvated clusters can be used as molecular models to investigate the photophysics and chemistry of aqueous electrolyte solutions.
Revised: April 19, 2005 |
Published: November 9, 2001
Citation
Wang X.B., X. Yang, J.B. Nicholas, and L.S. Wang. 2001.Bulk-Like Features in the Photoemission Spectra of Hydrated Doubly Charged Anion Clusters.Science 294, no. 5545:1322-1325.PNNL-SA-35319.