Berlin 2015 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 15: P1: Interfaces and Thin Films

CPP 15.9: Poster

Monday, March 16, 2015, 16:00–19:00, Poster A

Optical Tracking of Single Ag Clusters in Nanostructured Water Films — •Stefan Krause, Martin Hartmann, Ingolf Kahle, Martin Neumann, Mario Heidernätsch, Stefan Spange, and Christian von Borczyskowski — Technische Universität Chemnitz

Beside organic fluorescent molecules inorganic nano particles have attracted increasing attention as optical probes for soft matter during the past two decades. Especially the photo stability of inorganic materials makes them suitable as fluorescent labels and nano probes. Thereby the fluorescence of a single particle serves as a sensitive probe for its environment and changes of the fluorescence lifetime, emission wavelength, polarization and position can report spatial and temporal heterogeneities in the environment of the particles which are not accessible with ensemble methods. Here we report on the spatial diffusion of single silver nano clusters of the size of about one nano meter within structured water layers on pure SiO2. The diffusion reveals a twofold spatial heterogeneity of the water films. The interaction of water molecules with the surface results in an *ice-like* structuring of the first 2 to 3 mono layers while higher layers exhibit an unstructured, *water-like* formation of the molecules. In addition, irregularities in the density of surface silanols which can be influenced by different surface treatment processes leads to formation of lateral islands. As a result of this structuring diffusion shows immobile, slow and fast diffusing clusters. This experiment provides insights into the processes of water film formation and its heterogeneities.