Optical control of photogenerated ion pair lifetimes: An approach to a molecular switch

A prototype molecular switch is demonstrated that works on the principle that the local electric field produced by one photogenerated ion pair (D₁- A₁) can influence the rate constants for photoinduced electron transfer and recombination in a second donor-acceptor pair (A₂-D₂). Two ultrafast laser pulses were used to control the rate of a photoinduced electron transfer reaction within a molecule that consists of two covalently linked electron donor-acceptor pairs fixed in a linear structure, D₁-A₁-A₂-D₂. This type of molecular architecture may lead to the development of electronic devices that function on the molecular length scale.