Preparation, characterization, and photolysis of dodecanethiol-derivatizednoble metal nanoparticles

Dodecanethiol-derivatized nanoparticles of Ag, Ag/Au, and Au with an averag e size of 5.5 nm have been prepared via a two-phase synthetic route in wate r/toluene and characterized with various methods. In particular, their phot ochemical dynamics and mechanisms have been studied with laser flash photol ysis. The surface plasmon absorption peak varies linearly from 532 to 429 n m as the Ag fraction of Ag/Au alloy clusters, in which Ag atoms are more ab undant at the outer part, increases. Excited silver nanoparticles dispersed in cyclohexane undergo dethiolation in 8 ns and then fragmentation in 40 n s. Thereafter, the fragments gradually aggregate owing to the presence of l ess soluble bare metal sides.