Picosecond studies on the electron transfer from pyrene and perylene excited singlet states to N-hexadecyl pyridinium chloride

Abstract

Picosecond laser flash photolysis studies have been carried out on two aromatic solutes, pyrene (Py) and perylene (Pe), in methanolic and aqueous micellar solutions of a cationic surfactant, hexadecyl pyridium chloride (CPC) on excitation at 355 nm. In methanolic solutions, the addition of CPC quenches the singlet state of the aromatics giving rise to cation radicals, Py^+• and Pe^+•, respectively. The cation radicals either decay by geminate recombination or escape in the bulk solution phase in ≈ 1000 ps. In aqueous micellar solutions of CPC, only Py^+• is observed, while for Pe, initially both the singlet and the cation radical are observed immediately after the 35 ps laser pulse. The observed decay kinetics are explained in terms of electron transfer and geminate recombination processes.