Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 36: Posters: Bio/organic Molecules on Surfaces, Graphene, Solid/liquid interfaces, Metal Substrates, Electronic Structure Theory
O 36.65: Poster
Dienstag, 1. April 2014, 18:30–22:00, P1
Surface melting of ice — •M.Alejandra Sánchez1, Marc-Jan van Zadel1, Patrick Bisson2, Mary J. Shultz3, Mischa Bonn1, and Ellen H.G. Backus1 — 1Max Planck Institute for Polymer Research, Mainz, Germany — 2Dartmouth College, Thayer School of Engineering at Dartmouth, Hanover, USA — 3Laboratory for Water and Surface Studies, Chemistry Department, Tufts University, Medford, USA
Although ice is omnipresent on earth and in the atmosphere, its surface is poorly understood. It is well-known that a liquid-like layer is present on the surface of ice far below the bulk melting temperature of ice. However, there is intense debate on the microscopic nature of this interfacial melt. By using single crystal ice samples and Sum Frequency Generation (SFG) surface-specific vibrational spectroscopy, we aim to elucidate the nature of this layer. With SFG we obtain the vibrational spectrum of solely the interfacial molecules. Single Ih crystals rods of 2.5 cm diameter with a length of 20 cm are grown in a homebuilt ice machine based on the Bridgeman-Stockbarger method. By comparing SFG spectra at different temperatures varying from liquid water to ice, we obtain information about the hydrogen bond strength, and thus the nature, of the interfacial water molecules. Preliminary results show that at 258 K the water molecules are more strongly bonded than in liquid water at 293 K. In the future we will perform time resolved-SFG to elucidate the reorientational dynamics of the molecules at different temperatures, which gives additional information about the molecules' binding strength.