  Chains of metallic nanoparticles sustain strongly confined surface plasmons
with relatively low dielectric losses. To exploit these properties in
applications,such as waveguides, the fabrication of long chains of low disorder
and a thorough understanding of the plasmon-mode properties, such as dispersion
relations, are indispensable. Here, we use a wrinkled template for directed
self-assembly to assemble chains of gold nanoparticles. With this up-scalable
method, chain lengths from two particles (140 nm) to 20 particles (1500 nm) and
beyond can be fabricated. Electron energy-loss spectroscopy supported by
boundary element simulations, finite-difference time-domain, and a simplified
dipole coupling model reveal the evolution of a band of plasmonic waveguide
modes from degenerated single-particle modes in detail. In striking difference
from plasmonic rod-like structures, the plasmon band is confined in excitation
energy, which allows light manipulations below the diffraction limit. The
non-degenerated surface plasmon modes show suppressed radiative losses for
efficient energy propagation over a distance of 1500 nm.
