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Molecular Physics seminar

Studying water and aqueous TMAO solutions under high pressure and supercritical conditions

by Hendrik Vondracek (Ruhr-University Bochum)

FB55 ()


Studies of water under extreme conditions (high and low temperatures, extreme pressures) are of particular scientific interest. Understanding the properties of water under extreme conditions is not only a fundamental prerequisite for a better understanding of geological and biological processes and the exploitation of various technical applications, but is also widely believed to be fundamental for a deeper understanding of the structure of water under ambient conditions [1]. Under high pressures and temperatures to the supercritical regime, the structure of water and the hydrogen bond network show peculiar features, e.g. Clustering [2]. TMAO is an organic compound that is found in deep-sea fish in a concentration that is increasing with depth [3]. It is also known that it may counteract pressure-induced destabilization of proteins. However, the influence of TMAO on hydrogen-bonding under high-pressure conditions has not yet been studied. Our research project aims at investigating the change of hydrogen-bonding in water and aqueous TMAO solutions at high pressure and/or high temperature conditions by means of THz absorption spectroscopy. THz spectroscopy is an ideal tool to study the structural properties of water and aqueous solutions as it allows for a direct study of the intermolecular hydrogen-bond network. The principle of this spectroscopic technique and specific experimental challenges will be explained. Furthermore, first results of spectroscopic measurements of water under high pressure conditions will be presented. [1] A.Nilsson, L.G.M. Pettersson - Perspective on the structure of liquid water - Chem. Phys., 389,1-34 (2011). [2] Q.Sun, Q. Wang and D. Ding - Hydrogen Bonded Networks in Supercritical Water - J. Phys. Chem. B, 118, 11253-11258 (2014) [3] Yancey et al. - Marine fish may be biochemically constrained from inhabiting the deepest ocean depths, Proc. Natl. Acad. Sci. U. S. A., 111, 4461–4465 (2014)