Within the ERC Advanced Grant proposal GAS-WAT (Gases in water as probe of water structure) there are several postdoc positions available. Abstract below. Contact Lars G.M. Pettersson at [email protected] for further information.

Abstract

Is there “hidden” structure in normal liquid water? Do nanoscopic structural heterogeneities in ambient water exist and affect solution chemistry? In this project we will focus on structural fluctuations in simulations of liquid water as observed through the enhancement of the isothermal compressibility. From both experiment and theory a two-state picture of water is emerging with fluctuations between high- (HDL) and low-density (LDL) local structures. The structure of these is unknown. Moreover, present simulation models require a pressure shift of one thousand atmospheres to reproduce the experimental compressibility maximum at ambient pressure. We propose to develop a unique description of the liquid that extends to take into account that the water molecule exists in two forms, ortho and para, with different rotational properties. We will use Argon dissolved in water as discrete probe of the LDL local environments in high-resolution EXAFS measurements to discern their structure. Finally, in a two-state picture with LDL structures providing “pockets of stability” for dissolved oxygen, the question arises how fish entice the oxygen to leave the water and enter the gills. We will carry out a combined experimental X-ray spectroscopic and theoretical modeling study of water in polyelectrolyte and polysaccharide models of the mucous layer found outside lamella of fish gills and specifically determine how water structure there differs from the bulk. Has Nature through evolution found a way to restructure the water to enhance exchange of gases?