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 (D 1 + -A 1 − ) can influence the rate constants for photoinduced electron transfer and recombination in a second donor-acceptor pair (A 2 -D 2 ). 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, D 1 -A 1 -A 2 -D 2 . This type of molecular architecture may lead to the development of electronic devices that function on the molecular length scale.