SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 81: Oxide and Insulator Surfaces I: Adsorption and Reaction of Small Molecules
O 81.9: Vortrag
Donnerstag, 30. März 2023, 17:00–17:15, CHE 91
How the (2x1) Reconstruction of Calcite (10.4) dominates the Desorption Kinetics of Water and Ethanol — •Tobias Dickbreder1, Dirk Lautner2, Antonia Köhler1, Lea Klausfering1, Ralf Bechstein1, and Angelika Kühnle1 — 1Physical Chemistry I, Bielefeld University, 33615 Bielefeld, Germany. — 2Institute of Physical Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55099 Mainz, Germany.
Calcite, the most abundant carbonate mineral in the Earth's crust, plays a dominate role in a variety of environmental processes. Upon cleavage, calcite exposes the (10.4) cleavage plane with a rectangular unit cell. Interestingly, several experiments have been presented that suggest a (2x1) surface reconstruction. However, clear experimental evidence and a theoretical confirmation were long missing. Recently, an atomic force microscopy study provided convincing experimental indication for a (2x1) reconstruction at 5 K. Nevertheless, it remained unclear how the (2x1) reconstruction effects the surface properties of calcite. Here, we present temperature-programmed desorption (TPD) curves of water and ethanol desorbing from calcite (10.4) around room temperature. Our experiments can be excellently described by a kinetic model considering two different adsorption positions, as would be present in case of a (2x1) reconstruction. This finding applies to the desorption of water and ethanol, suggesting that the effect is not molecule specific, but characteristic for the calcite cleavage plane. Our results, thus, demonstrate that the (2x1) reconstruction has significant impact on the interfacial properties of calcite.