Photoinduced Charge Separation in a Fluorophore−Gold Nanoassembly

We report the first spectroscopic demonstration of direct electron transfer between a gold nanoparticle and a surface-bound fluorophore induced by pulsed laser irradiation. Binding of pyrene thiol directly to the gold nanoparticle results in quenching of its singlet excited state. The suppression of S1−T1 intersystem crossing process as well as the formation of pyrene radical cation confirm the excited-state interaction between the metal nanoparticle and the surface-bound fluorophore. The charge separation is sustained for several microseconds before undergoing recombination.