Sur ce site

Sur le Web du CNRS


Accueil du site > Productions scientifiques > Séminaires à PHENIX > 2010 > Cours


par Guillaume Mériguet - 27 août 2010

Le professeur Vojko Vlachy, de l’université de Ljubljana (Slovénie), professeur Invité par l’UPMC au laboratoire PECSA, dispensera deux séances de cours :

Ions in water :
From Debye-Hückel limiting law to ion-specific effects in presence of hydrophobic groups

Lieu :
Bibliothèque du laboratoire PECSA, Campus Jussieu Bât. F74, 7e étage - pièce 754

Cours 1 : Lundi 12 avril 2010, 14h30-16h30

I will start the lecture with the classical Born model of solvation, emphasizing that ion-water interaction to a large degree influences the behavior of electrolyte solutions. I shall continue with reviewing the Debye-Hückel (D-H) theory : definitions for the osmotic coefficient and enthalpy of dilution will be introduced first. The Debye-Hückel results will be compared with experimental data for these two quantities. Next I will introduce the pair-distribution formalism and the Ornstein-Zernike (O-Z) integral equation theory. The mean-field approximations, inherent to the D-H theory, will be discussed in light of the O-Z integral equation. The Debye-Hückel screened potential will be derived within the integral equation approach by using a suitable approximation.

Cours 2 : Mardi 13 avril 2010, 14h30-16h30

An example of the "civilized" model of solution, where ions and water molecules are treated on equal footing will be introduced. The crystal sizes of individual ions will be used as major parameters of the model. The Wertheim O-Z theory will be utilized to obtain the osmotic coefficient results. I will show that the model successfully explains the ion-specific effects in alkali halide solutions, rationalizing the "Law of matching water affinities". The last part will be dedicated to influence of hydrophobic groups on the interaction between charged groups on polyions and the ions in solution. On the basis of our new experimental data and all atom simulations we will show how the presence of hydrophobic groups modifies the ion- specific effects.