This work deals with the optical properties of supported noble metal nanoparticles,
which are dominated by the so-called Mie resonance and are strongly dependent
on the particles’ morphology. For this reason, characterization and control of the
dimension of these systems are desired in order to optimize their applications. Gold
and silver nanoparticles have been produced on dielectric supports like quartz glass,
sapphire and rutile, by the technique of vapor deposition under ultra-high vacuum
conditions. During the preparation, coalescence is observed as an important mechanism
of cluster growth. The particles have been studied in situ by optical transmission
spectroscopy and ex situ by atomic force microscopy. It is shown that the
morphology of the aggregates can be regarded as oblate spheroids. A theoretical
treatment of their optical properties, based on the quasistatic approximation, and
its combination with results obtained by atomic force microscopy give a detailed
characterization of the nanoparticles. This method has been compared with transmission
electron microscopy and the results are in excellent agreement. Tailoring of
the clusters’ dimensions by irradiation with nanosecond-pulsed laser light has been
investigated. Selected particles are heated within the ensemble by excitation of the
Mie resonance under irradiation with a tunable laser source. Laser-induced coalescence
prevents strongly tailoring of the particle size. Nevertheless, control of the
particle shape is possible. Laser-tailored ensembles have been tested as substrates for
surface-enhanced Raman spectroscopy (SERS), leading to an improvement of the results.
Moreover, they constitute reproducible, robust and tunable SERS-substrates
with a high potential for specific applications, in the present case focused on environmental
protection. Thereby, these SERS-substrates are ideally suited for routine
measurements.