Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: Poster: Nanoparticles and Composite Materials

CPP 8.5: Poster

Monday, March 26, 2012, 17:30–20:00, Poster A

Growth of silver nanowires within nanotubular J-aggregates — •Egon Steeg, Holm Kirmse, Jürgen P. Rabe, and Stefan Kirstein — Institut für Physik, Humboldt-Universität zu Berlin

It was demonstrated earlier that ultrathin but long Ag nanowires with a diameter less than 7 nanometers and a length exceeding micrometers can be fabricated by reduction of silver salt using uniform nanotubular J-aggregates of amphiphilic cyanine dyes as template [1]. Here we report on the growth mechanism of these Ag wires as revealed by transmission electron microscopy. The growth of the wires is photo-initiated by short illumination with blue light and is terminated at different time steps by removing Ag⁺ ions upon adding NaCl to the solution. In this case the Ag⁺ ions react with the Cl⁻ ions to form AgCl nanocrystals. At times shorter than 2 hours, small and well separated fragments of silver wires are found along the aggregates with a broad length distribution in the range of ten to hundred nanometers. At times later than 2 hours, homogeneous wires are found with lengths of microns filling almost the entire aggregates. By high-resolution TEM one finds microcrystalline domains with sizes up to 100 nm. These findings show that the growth of the wires starts independently at distinct nucleation centers and proceeds to fill the entire aggregate. This growth process must be supported by transport of Ag⁺ ions through the tubular wall membrane.

[1] D.M. Eisele et al., J. Am. Chem. Soc. 132 (2010) 2104.