Pulsed infrared laser annealing of gold nanoparticles embedded in a silica matrix...

Pulsed infrared laser irradiation was used to modify the optical and physical properties of gold
nanoparticles in a SiO2 substrate. The primary laser wavelength used for annealing was 8 ?m,
where the primary absorption is in the substrate. The optical absorption spectra exhibit a typical
surface plasmon peak at 520 nm, which increases with laser fluence. This implies growth of the
gold nanoparticles during laser annealing but the size distribution remains narrow, unlike some
thermal annealing procedures that produce bimodal size distributions. The results were confirmed
by scanning transmission electron microscopy, and are consistent with calculations of the expected
extinction spectra.