Dresden 2014 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 54: Poster Session 3
CPP 54.21: Poster
Donnerstag, 3. April 2014, 15:00–19:00, P2
Dielectric effects of sodium salts in aqueous solution — •Klaus Friedrich Rinne1, Stephan Gekle2, and Roland Netz1 — 1Fachbereich Physik, Freie Universität Berlin, 14195 Berlin — 2Nachwuchsgruppe Theoretische Physik, Universität Bayreuth, 95440 Bayreuth
We present dielectric spectra obtained from equilibrium molecular dynamics simulations of 1 molar aqueous solutions (SPC/E water) of NaF, NaCl, NaBr and NaI. The ion specific static and dynamic effects match experiments results. Additionally, sodium chloride is studied concentration dependently.
The dielectric contribution of the water-polarisation auto-correlation is decomposed into different groups depending on solvation shells and the pair state of the nearest ion. It is shown that even second and third solvation shell water is affected by dielectric saturation leading to a red shift of the spectra compared to bulk water.
Moreover, the contribution of the water-ion polarisation cross-correlation is included leading to a reduction of total dielectric signal by 5-10%. A continuous trend of the cross-correlation with increasing anion size is observed. For the first time the ion pairs are grouped in different ion pair configurations showing that the static equivalent conductance of a contact ion pair is about 50% lower than for ion pairs with larger separation. Furthermore, we show the dynamic ion current auto-correlation contributes about one percent to the total static dielectric constant of the solution.