8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Fri 911:10-14:00P1.19Dynamics and transport of ions in supercritical fluidsunder the action of an electrostatic fieldAndreas Koutselos, 1 Maria Anagnostopoulou, 1 Hercules Litinas, 1 and JannisSamios 11 University of Athens, University of Athens, Chemistry Department, Panepistimiopolis15771, Athens, GreeceThe emergence of a density variation around solutes at supercritical fluids affects their dynamicand mean motion and in addition it can modify chemical equilibria and reaction rates. The molecularmotion of the ions and electrons in such states under the action of an electric field dependsmainly on the enhanced density inhomogeneities of the fluid [1] and the charged particle-neutralmedium interactions. We have studied the dynamics and the transport of ions in supercriticalsimple fluids by developing a nonequilibrium molecular dynamics method that simulates theaction of the electrostatic field and the thermal dissipation through an effective molecular process.[2] The density and field dependence of the ion properties along an isotherm above the criticaltemperature is explained by the structure and the dynamics of the solvation shell that surroundsthe ion. In the case of O 2 - in supercritical Ar, the ion mobility is found to acquire a minimumclose to the critical density in accordance with the experiment, [3] using a model potential energysurface that is based on ab-initio quantum calculations. This feature can be explained by thecharacteristics of the shell structure of Ar around the ion, below and above the critical point.[1] I. Skarmoutsos, D. Dellis, and J. Samios, J. Chem. Phys. 126, 224503 (2007 ); J.Phys. Chem. B. 113, 2783 (2009).[2] G. Balla and A. D. Koutselos, J. Chem. Phys. , 119, 11374 (2003).[3] A. F. Borghesani and F. Tamburini, Phys. Rev. Lett. 83, 4546 (1999).19