par Gilis, Natalia ;Prakash, Jai ;Franke, Jorn Holger ;Visart de Bocarmé, Thierry
Référence Interdisciplinary Surface Science Conference (20: 2015/04/02: Brimingham)
Publication Non publié, 2015-04-02
Communication à un colloque
Résumé : Chirality at surfaces has become an active research area targeting possible applications of enantioselective separation or detection. In this context, significant success has been achieved these past decades by developing new methods for a better understanding of enantiospecific interactions of chiral adsorbate with surfaces. Here, we propose a promising route for obtaining fundamental understanding of enantiospecific interaction of chiral molecules on metal surfaces using field emission based techniques. This technique has been chosen for its particular advantage to expose a wide range of structurally different facets in one atomically resolved picture. This diversity allows us to screen with one sample the interactions between a chemical species and a number of facets during the adsorption process.In the present study, we envisage the adsorption of alanine on platinum surfaces modelled as sharp tip using field emission and field microscopy along with theoretical studies using density functional theory.In order to observe the adsorption pattern of the adsorption, the Pt surface is kept at temperatures between 150 and 300K, and then exposed to vapors of D or L-alanine. The in-situ FEM is filmed with a high-speed camera. The whole process is also performed in absence of alanine molecules to perform reference experiments. The subtraction of the results before and after the adsorption gives us a net image of the adsorption sites. Our results show a clear preference of the alanine to adsorb on chiral facets. Although the 20 Å resolution of the FEM does not allow to unravel the edges of the facets of interest, the net images after exposures to one enantiomer of alanine show the occurrence of an enantioselective adsorption over sector of the same chiral symmetry. The results show that L-alanine has a strong tendency to adsorb onto R facets. Conversely, D-alanine adsorbs onto the S facets.