Ion Distributions near a Liquid-Liquid Interface
Guangming Luo,1
Sarka Malkova,1
Jaesung Yoon,1
David G. Schultz,1,2
Binhua Lin,3
Mati Meron,3
Ilan Benjamin,4
Petr Van
sek,5
Mark L. Schlossman1,2*
Mean field theories of ion distributions, such as the Gouy-Chapman theory that describes the distribution near a charged planar surface, ignore the molecular-scale structure in the liquid solution. The predictions of the Gouy-Chapman theory vary substantially from our x-ray reflectivity measurements of the interface between two electrolyte solutions. Molecular dynamics simulations, which include the liquid structure, were used to calculate the potential of mean force on a single ion. We used this potential of mean force in a generalized Poisson-Boltzmann equation to predict the full ion distributions. These distributions agree with our measurements without any adjustable parameters.
1 Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA.
2 Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA.
3 Center for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637, USA.
4 Department of Chemistry, University of California, Santa Cruz, CA 95064, USA.
5 Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115, USA.
* To whom correspondence should be addressed. E-mail: schloss{at}uic.edu
