Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Inorganic/Organic Interfaces

O 41.22: Poster

Dienstag, 17. März 2015, 18:15–21:00, Poster B

Crystallization of Tris-HCl on gold and mica surfaces — •Seyma Nayir, Merve Altay, Toprak Ayaz, Ilker Oztoprak, and Oguzhan Gurlu — Istanbul Technical University, Istanbul, Turkey

Tris molecule crystallizes in the orthorhombic system with a layered structure. Previously we have shown that precipitates from Tris-EDTA-HCl buffer solution crystallize on Au surfaces by forming hexagonal structures. We had shown that Tris-HCl, a component of Tris-EDTA-HCl buffer solution, was the main reason of such crystallites. In this study we investigated the crystallization behavior of Tris-HCl on mica, Au/mica and Au/Cr/mica surfaces from different solutions with various molarities. The samples were prepared by drop-casting of the solution on to surfaces and they were investigated by optical and probe microscopy techniques. Our data indicated that surface roughness directly affects the crystallization behavior of Tris-HCl from the drying droplet, and formation of hexagonal structures depends on the roughness and hydrophobicity of the surfaces. We have observed that the crystallization starts mostly on the rough edges/surfaces and the completed crystallites cover the underlying surface roughness totally. On the other hand we rarely observed hexagonal crystals on initially flat and smooth gold surfaces while they formed on freshly cleaved mica surfaces. We speculate that formations of such structures are strongly related to the electrostatic landscape of substrates used which we investigated by means of Kelvin Probe Microscopy.