Quenching and Enhancement of Fluorescence of Dye Molecule on Negative and Positive Colloid Silver Particles

Both negatively and positively charged colloids (in brief, PCS and NCS) of silver nano-particles were prepared. Quenching and enhancement of fluorescence fromrhodamine (RhB) and Fluorescein sodium (FS) molecules on the two colloids of silver nano-particles were recorded respectively and compared with each other. On PCS, the fluorescence of RhB is enhanced when the concentration is low, whilst when the concentration is high the fluorescence of RhB is quenched. However for FS, the fluorescence is always enhanced. On NCS, the fluorescence of FS and RhB are quenched.