Composition and chemistry at the liquid/vapor interface of aqueous solutions: Comparisons between experiment and MD simulations

COMP 67

John C Hemminger, jchemmin@uci.edu1, Matthew A. Brown1, Maria J. Krisch, mkrisch@uci.edu1, David E Starr, destarr@lbl.gov2, Simon Mun2, and Hendrik Bluhm2. (1) Department of Chemistry and AirUCI, University of California at Irvine, Irvine, CA 92697, (2) Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
We use ambient pressure photoelectron spectroscopy (HPPES) experiments carried out at beam lines 11.0.2 and 9.3.2 of the Advanced Light Source at Lawrence Berkeley National Laboratory to probe the liquid/vapor interface of aqueous solutions. Using HPPES we can obtain the composition at the surface of liquid samples in contact with vapor pressures up to several torr. The vapor phase of the experiment can include reactive components (e.g., ozone) in addition to the equilibrium vapor associated with the liquid. By varying the x-ray energy, and thus the photoelectron kinetic energy, the experimental probe depth into the solution can be varied systematically. The ion concentrations in the near surface region of pure salt solutions and salt solutions coated with an organic surfactant layer will be described. Systems that will be discussed include aqueous solutions of the potassium halide salts and aqueous solutions of sodium nitrate. Reactions of ozone with solutions of KI will also be described. Comparisons between experiments and MD simulations will be discussed.