Electron spectroscopy of agueous solution interfaces revealssurface enhancement of halides
It has been suggested that enhanced anion concentrations at the liquid/vapor interface of airborne saline droplets are important to aerosol reactions in the atmosphere. We report ionic concentrations in the surface of such solutions. Using x-ray photoelectron spectroscopy operating at near ambient pressure, we have measured the composition of the liquid/vapor interface for deliquesced samples of potassium bromide and potassium iodide. In both cases, the surface composition of the saturated solution is enhanced in the halide anion compared with the bulk of the solution. The enhancement of anion concentration is more dramatic for the larger, more polarizable iodide anion. By varying photoelectron kinetic energies, we have obtained depth profiles of the liquid/vapor interface. Our results are in good qualitative agreement with classical molecular dynamics simulations. Quantitative comparison between the experiments and the simulations indicates that the experimental results exhibit more interface enhancement than predicted theoretically.
- Research Organization:
- Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
- Sponsoring Organization:
- USDOE Director. Office of Science. Office of Basic EnergySciences; National Science Foundation Grants 0080806 and 0209719 and0431312; Alexander von Humbooldt Foundation, Consejo Nacional deInvestigaciones Cientificas y Tecnicas/Argentina
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 908158
- Report Number(s):
- LBNL--56811; BnR: KC0302030
- Journal Information:
- Science, Journal Name: Science Vol. 307; ISSN 0193-4511; ISSN SCEHDK
- Country of Publication:
- United States
- Language:
- English
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