Photoexcited fullerene species in Triton-X100 micelles

Abstract

Photoexcited states of fullerene C₆₀ have been studied using laser flash photolysis and near-IR spectroscopy. In order to stabilise these species the C₆₀ molecules were incorporated into aqueous micelles of reduced Triton-X100 (TX100-R). Mechanistic studies show that C₆₀ ⁻ can be formed in the presence of an electron donor, such as sodium ascorbate, via the triplet state ³C₆₀. With this donor at 0.25 mmol dm⁻³, a maximum lifetime for C₆₀ ⁻ of τ ≈ 400 s was obtained. For the parent micelles the c.m.c.s. were measured using dye solubilisation and the aggregation structures were investigated by small-angle neutron scattering (SANS). The levels of additives used here did not significantly affect either of these micellar properties. To see if aggregate breakdown is an important step in the C₆₀ ⁻ decay pathway the micelle lifetimes were investigated using stopped-flow spectrophotometry. Finally, a mechanism for C₆₀ ⁻ formation/decay is proposed that is consistent with all these results.