2,661 research outputs found
Ions at the air-water interface: An end to one hundred year old mystery?
Availability of highly reactive halogen ions at the surface of aerosols has
tremendous implications for the atmospheric chemistry. Yet neither simulations,
experiments, nor existing theories are able to provide a fully consistent
description of the electrolyte-air interface. In this paper a new theory is
proposed which allows us to explicitly calculate the ionic density profiles,
the surface tension, and the electrostatic potential difference across the
solution-air interface. Predictions of the theory are compared to experiments
and are found to be in excellent agreement. The theory also sheds new light on
one of the oldest puzzles of physical chemistry -- the Hofmeister effect
Ion specificity and the theory of stability of colloidal suspensions
A theory is presented which allow us to accurately calculate the critical
coagulation concentration (CCC) of hydrophobic colloidal suspensions. For
positively charged particles the CCC's follow the Hofmeister (lyotropic)
series. For negatively charged particles the series is reversed. We find that
strongly polarizable chaotropic anions are driven towards the colloidal surface
by electrostatic and hydrophobic forces. Within approximately one ionic radius
from the surface, the chaotropic anions loose part of their hydration sheath
and become strongly adsorbed. The kosmotropic anions, on the other hand, are
repelled from the hydrophobic surface. The theory is quantitatively accurate
without any adjustable parameters. We speculate that the same mechanism is
responsible for the Hofmeister series that governs stability of protein
solutions.Comment: Phys. Rev. Lett. (in press
Reply to 'Comment on "Vortex distribution in a confining potential"
We argue that contrary to recent suggestions, non-extensive statistical
mechanics has no relevance for inhomogeneous systems of particles interacting
by short-range potentials. We show that these systems are perfectly well
described by the usual Boltzmann-Gibbs statistical mechanics
Lattice Model of an Ionic Liquid at an Electrified Interface
We study ionic liquids interacting with electrified interfaces. The ionic
fluid is modeled as a Coulomb lattice gas. We compare the ionic density
profiles calculated using a popular modified Poisson-Boltzmann equation with
the explicit Monte Carlo simulations. The modified Poisson-Boltzmann theory
fails to capture the structural features of the double layer and is also unable
to correctly predict the ionic density at the electrified interface. The
lattice Monte Carlo simulations qualitatively capture the coarse-grained
structure of the double layer in the continuum. We propose a convolution
relation that semiquantitatively relates the ionic density profiles of a
continuum ionic liquid and its lattice counterpart near an electrified
interface
- …