Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 18: Solid-liquid Interfaces II

O 18.12: Talk

Monday, March 31, 2014, 18:45–19:00, WIL A317

Exploring the formation, lifetime and dissociation statistics of acid-amine bonds — •Sangeetha Raman and Markus Valtiner — Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH, D-40237, Düsseldorf, Germany

Understanding the scaling of single molecular interaction forces towards an integral interaction between extended surfaces interacting simultaneously through a large number of molecular bonds is a key objective in order to model or predict interactions in realistic situations. Here we study the scaling of interaction forces arising from acid-base bond at both, the single molecular level using force spectroscopy with atomic force microscopy (AFM) and the macroscopic level using surface forces apparatus experiments (SFA). The single molecule experiments reveal two distinct regimes of interaction forces as a function of the bond-loading rate - the equilibrium desorption regime and the force-dependent bond dissociation regime. SFA measurements revealed, that the forces measured in the equilibrium regime using AFM, scale linear with the number density of acid base bonds at the interface. We show that a combined approach of AFM and SFA allows for a detailed understanding of both kinetic aspects of the bond forming and breaking as well as equilibrium scaling of the interaction forces. AFM allows to directly measuring lifetimes of bonds, while SFA allows to directly studying the equilibrium interactions between specific bonds. Our results provide complementary information to predict and model realistic situations of bond forming and breaking.