Segregation of salt ions at amorphous solid and liquid surfaces
Traditionally, the surfaces of aqueous electrolytes are described as inactive and practically devoid of ions [1, 2]. Indeed, this has turned out to be true for non - polarizable ions, as alkali cations and small anions, as fluoride as well. However, due to polarization interactions singly charged anions, with the heavy halides as particular examples, exhibit a propensity for the water / air (vacuum) interface. This was first suggested in order to rationalize the occurrence of chemical reactions on aqueous interfaces, sea - salt particles, ocean surfaces etc. This initiated MD calculations using polarizable potentials. They suggest that highly polarisable anions can indeed be preferentially adsorbed at the outermost liquid layer. In this description, the ions are polarized by the anisotropy of the interface, creating an induced dipole that is stronger than in the bulk. The interaction between the polarized ions and the surrounding water molecules compensates for the reduced solvation available at the surface. This has triggered a number of laboratory studies, applying mainly non - linear optical probes. Battelle operates Pacific Northwest National Laboratory for the US Department of Energy.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 921582
- Report Number(s):
- PNNL-SA-56192; KC0301020
- Country of Publication:
- United States
- Language:
- English
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