  The synthesis of silver nanowires in solution phase is of great interest
because of their applicability for fabrication of plasmonic devices. Silver
nanowires with diameters of 6.5 nm and length exceeding microns are synthesized
in aqueous solution by reduction of silver ions within the nanotubular
J-aggregates of an amphiphilic cyanine dye. The time scale of the growth of the
nanowires is of the order of hours and days which provides the unique
possibility to investigate the nucleation, growth, and dissolution of the
nanowires by direct imaging using transmission electron microscopy. It is found
that the initial nucleation and formation of seeds of silver nanostructures
occurs randomly at the outer surface of the aggregates or within the hollow
tube. The growth of the seeds within the inner void of the tubular structures
to nanowires indicates transport of silver atoms, ions, or clusters through the
bilayer wall of the molecular aggregates. This permeability of the aggregates
for silver can be utilized to dissolve the preformed silver wires by oxidative
etching using Cl- ions from dissolved NaCl. Although the nanosystem presented
here is a conceptual rather simple organic-inorganic hybrid, it exhibits growth
and dissolution phenomena not expected for a macroscopic system. These
mechanisms are of general importance for both, the growth and the usage of such
metal nanowires, e.g. for plasmonic applications.
