INTERPARTICLE ELECTRON-TRANSFER IN METAL SEMICONDUCTOR COMPOSITES - PICOSECOND DYNAMICS OF CDS-CAPPED GOLD NANOCLUSTERS/

Composite nanoclusters of gold and CdS with core/shell geometry have b een synthesized using a chemical precipitation method in aqueous media . These nanoclusters are photoactive and exhibit transient bleaching i n the 400-600 nm region when subjected to 355 nm laser pulse excitatio n. Capping of gold colloids with ultrasmall CdS nanoclusters (particle diameter similar to 4 nm) significantly alters the picosecond dynamic s of the gold core. The bleaching of the surface plasmon absorption of the gold core is achieved by exciting the CdS shell. The major fracti on of the interparticle electron transfer between CdS and Au nanoclust ers is completed within the laser pulse duration of 18 ps.