Electronic Dephasing in Bimetallic Gold-Silver Nanoparticles Examined by Single Particle Spectroscopy

The scattering spectra of single gold, silver, bimetallic gold-silver particles (both core-shell and alloyed) were recorded by dark field microscopy. The results show that core-shell nanoparticles have broader scattering spectra than the corresponding pure gold or silver nanoparticles. However, plots of the width of the plasmon resonance versus resonance frequency for the core-shell and alloyed samples are very similar. This observation implies that the broadening is mainly caused by the frequency dependence of the imaginary component of the dielectric constants of the particles. For the core-shell particles scattering at the interface between the two metals does not seem to be a significant effect.