Electrochemical preparation of silver and gold nanoparticles: Characterization by confocal and surface enhanced Raman microscopy

The maximum SERS enhancement factors found in the measurements were: (i) 1010 for silver particles and (ii) 108 for gold particles. The optical and spectroscopic data of the local nanoparticle structures investigated showed that SERS is a local phenomenon, because (i) only few particles are Raman active particles, (ii) strongest enhancements in SERS are obtained from particle agglomerates, (iii) typically the Raman radiation is emitted from irregular structures like the necks between two or more particles agglomerated. In the investigated range from 10 to 500 nm no significant influence of the particle size was observed.