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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid/liquid interfaces; Metals; Semiconductors; Oxides and insulators)

O 58.37: Poster

Wednesday, March 28, 2012, 18:15–21:45, Poster B

Planar gold nano crystals as photonic substrate for single-molecule mechano-optical investigations — •Sören Grannemann, Tamara Münnich, Volker Walhorn, and Dario Anselmetti — Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld University, Germany

The combination of scanning probe microscopy and optical microscopy techniques is a valuable tool for biological and biomedical investigations at the single molecule level. For these investigations transparent substrates are needed that allow easy sample immobilization. Thin (approx. 20nm) gold films are (quasi) transparent materials whose surface modification by thiol-chemistry is easy and well established. Planar gold nano crystals (PGNC) grown via the thermal aqueous solution method [1] exhibit sizes ranging from some 100 nm to several microns while their thickness lies in the range of roughly 20 nm. Furthermore, the Gold (111) surface is atomically smooth and ideally allows for the immobilization of self-assembled monolayers. We synthesized PGNC and immobilized them on indium tin oxide (ITO) coated glass cover slips. The nano-crystals were investigated by atomic force microscopy (AFM) to characterize their size, thickness and surface roughness. Furthermore, the excitation and detection of single molecule fluorescence through the PGNC by total internal reflection fluorescence (TIRF) microscopy is demonstrated. Therefore, we modified the immobilized PGNC with a mercapto-alkyl self-assembled monolayer exhibiting sparsely distributed amino moieties for dye attachment. [1] H.-C. Chu, C.-H. Kuo and M. H. Huang, Inorg. Chem., 808, 2006.