Communication: Delayed asymmetric Coulomb fission of molecular clusters: application of a dielectric liquid-drop model.

Delayed asymmetric Coulomb fission in size-selected molecular dication clusters has been recorded for the first time. Observations on (NH(3))(n)(2+) clusters show that fragmentation accompanied by charge separation can occur on a microsecond time scale, exhibits considerable asymmetry, and involves a kinetic energy release of ∼0.9 eV. The fission process has been modeled by representing the fragments as charged dielectric spheres and the calculated maximum in the electrostatic interaction energy between the fragments gives a good account of the measured kinetic energy release. A simple kinetic model shows that instrumental factors may contribute to the observation of asymmetric fragmentation.